SERVER-31802 Rip out more dead master-slave code, and the related concept of RID.

44 files changed, 48 insertions, 783 deletions

diff --git a/src/mongo/client/embedded/replication_coordinator_embedded.cpp b/src/mongo/client/embedded/replication_coordinator_embedded.cpp
index c257f050e33..affd8a085ba 100644
--- a/src/mongo/client/embedded/replication_coordinator_embedded.cpp
+++ b/src/mongo/client/embedded/replication_coordinator_embedded.cpp
@@ -178,10 +178,6 @@ void ReplicationCoordinatorEmbedded::signalUpstreamUpdater() {
     UASSERT_NOT_IMPLEMENTED;
 }
 
-Status ReplicationCoordinatorEmbedded::setLastOptimeForSlave(const OID&, const Timestamp&) {
-    UASSERT_NOT_IMPLEMENTED;
-}
-
 void ReplicationCoordinatorEmbedded::setMyHeartbeatMessage(const std::string&) {
     UASSERT_NOT_IMPLEMENTED;
 }
@@ -241,10 +237,6 @@ OID ReplicationCoordinatorEmbedded::getElectionId() {
     UASSERT_NOT_IMPLEMENTED;
 }
 
-OID ReplicationCoordinatorEmbedded::getMyRID() const {
-    UASSERT_NOT_IMPLEMENTED;
-}
-
 int ReplicationCoordinatorEmbedded::getMyId() const {
     UASSERT_NOT_IMPLEMENTED;
 }
@@ -336,10 +328,6 @@ Status ReplicationCoordinatorEmbedded::processReplSetUpdatePosition(const Update
     UASSERT_NOT_IMPLEMENTED;
 }
 
-Status ReplicationCoordinatorEmbedded::processHandshake(OperationContext*, const HandshakeArgs&) {
-    UASSERT_NOT_IMPLEMENTED;
-}
-
 bool ReplicationCoordinatorEmbedded::buildsIndexes() {
     UASSERT_NOT_IMPLEMENTED;
 }
diff --git a/src/mongo/client/embedded/replication_coordinator_embedded.h b/src/mongo/client/embedded/replication_coordinator_embedded.h
index e131b8e9449..6e6e9368936 100644
--- a/src/mongo/client/embedded/replication_coordinator_embedded.h
+++ b/src/mongo/client/embedded/replication_coordinator_embedded.h
@@ -102,8 +102,6 @@ public:
 
     Status checkIfWriteConcernCanBeSatisfied(const WriteConcernOptions&) const override;
 
-    Status setLastOptimeForSlave(const OID&, const Timestamp&) override;
-
     void setMyLastAppliedOpTime(const repl::OpTime&) override;
     void setMyLastDurableOpTime(const repl::OpTime&) override;
 
@@ -125,8 +123,6 @@ public:
 
     OID getElectionId() override;
 
-    OID getMyRID() const override;
-
     int getMyId() const override;
 
     Status setFollowerMode(const repl::MemberState&) override;
@@ -180,8 +176,6 @@ public:
 
     Status processReplSetUpdatePosition(const repl::UpdatePositionArgs&, long long*) override;
 
-    Status processHandshake(OperationContext*, const repl::HandshakeArgs&) override;
-
     bool buildsIndexes() override;
 
     std::vector<HostAndPort> getHostsWrittenTo(const repl::OpTime&, bool) override;
diff --git a/src/mongo/db/catalog/database_impl.cpp b/src/mongo/db/catalog/database_impl.cpp
index e6cc8ef537c..3e3b1871a2e 100644
--- a/src/mongo/db/catalog/database_impl.cpp
+++ b/src/mongo/db/catalog/database_impl.cpp
@@ -504,14 +504,10 @@ Status DatabaseImpl::dropCollectionEvenIfSystem(OperationContext* opCtx,
 
     // Drop unreplicated collections immediately.
     // If 'dropOpTime' is provided, we should proceed to rename the collection.
-    // Under master/slave, collections are always dropped immediately. This is because drop-pending
-    // collections support the rollback process which is not applicable to master/slave.
     auto replCoord = repl::ReplicationCoordinator::get(opCtx);
     auto opObserver = opCtx->getServiceContext()->getOpObserver();
     auto isOplogDisabledForNamespace = replCoord->isOplogDisabledFor(opCtx, fullns);
-    auto isMasterSlave =
-        repl::ReplicationCoordinator::modeMasterSlave == replCoord->getReplicationMode();
-    if ((dropOpTime.isNull() && isOplogDisabledForNamespace) || isMasterSlave) {
+    if (dropOpTime.isNull() && isOplogDisabledForNamespace) {
         auto status = _finishDropCollection(opCtx, fullns, collection);
         if (!status.isOK()) {
             return status;
diff --git a/src/mongo/db/clientcursor.cpp b/src/mongo/db/clientcursor.cpp
index 27d851fa043..f960afc60d7 100644
--- a/src/mongo/db/clientcursor.cpp
+++ b/src/mongo/db/clientcursor.cpp
@@ -129,23 +129,6 @@ void ClientCursor::dispose(OperationContext* opCtx) {
     _disposed = true;
 }
 
-void ClientCursor::updateSlaveLocation(OperationContext* opCtx) {
-    if (_slaveReadTill.isNull())
-        return;
-
-    verify(_nss.isOplog());
-
-    Client* c = opCtx->getClient();
-    verify(c);
-    OID rid = repl::ReplClientInfo::forClient(c).getRemoteID();
-    if (!rid.isSet())
-        return;
-
-    repl::ReplicationCoordinator::get(opCtx)
-        ->setLastOptimeForSlave(rid, _slaveReadTill)
-        .transitional_ignore();
-}
-
 //
 // Pin methods
 //
diff --git a/src/mongo/db/clientcursor.h b/src/mongo/db/clientcursor.h
index b811fc47722..42e7c20f069 100644
--- a/src/mongo/db/clientcursor.h
+++ b/src/mongo/db/clientcursor.h
@@ -212,23 +212,6 @@ public:
         _leftoverMaxTimeMicros = leftoverMaxTimeMicros;
     }
 
-    //
-    // Replication-related methods.
-    //
-
-    // Used to report replication position only in master-slave, so we keep them as TimeStamp rather
-    // than OpTime.
-    void updateSlaveLocation(OperationContext* opCtx);
-
-    void slaveReadTill(const Timestamp& t) {
-        _slaveReadTill = t;
-    }
-
-    /** Just for testing. */
-    Timestamp getSlaveReadTill() const {
-        return _slaveReadTill;
-    }
-
     /**
      * Returns the server-wide the count of living cursors. Such a cursor is called an "open
      * cursor".
@@ -325,9 +308,6 @@ private:
     // See the QueryOptions enum in dbclientinterface.h.
     const int _queryOptions = 0;
 
-    // The replication position only used in master-slave.
-    Timestamp _slaveReadTill;
-
     // Unused maxTime budget for this cursor.
     Microseconds _leftoverMaxTimeMicros = Microseconds::max();
 
diff --git a/src/mongo/db/commands/feature_compatibility_version.h b/src/mongo/db/commands/feature_compatibility_version.h
index feb7a8190f9..727ef8529fe 100644
--- a/src/mongo/db/commands/feature_compatibility_version.h
+++ b/src/mongo/db/commands/feature_compatibility_version.h
@@ -41,7 +41,7 @@ class OperationContext;
 
 /**
  * Startup parameter to ignore featureCompatibilityVersion checks. This parameter cannot be set if
- * the node is started with --replSet, --master, or --slave. This should never be set by end users.
+ * the node is started with --replSet. This should never be set by end users.
  */
 extern bool internalValidateFeaturesAsMaster;
 
diff --git a/src/mongo/db/op_observer_impl.cpp b/src/mongo/db/op_observer_impl.cpp
index c343ff63050..c8a470f5b91 100644
--- a/src/mongo/db/op_observer_impl.cpp
+++ b/src/mongo/db/op_observer_impl.cpp
@@ -93,14 +93,6 @@ repl::OpTime logOperation(OperationContext* opCtx,
 }
 
 /**
- * Returns whether we're a master using master-slave replication.
- */
-bool isMasterSlave(OperationContext* opCtx) {
-    return repl::ReplicationCoordinator::get(opCtx)->getReplicationMode() ==
-        repl::ReplicationCoordinator::modeMasterSlave;
-}
-
-/**
  * Updates the session state with the last write timestamp and transaction for that session.
  *
  * In the case of writes with transaction/statement id, this method will be recursively entered a
@@ -316,7 +308,7 @@ void OpObserverImpl::onCreateIndex(OperationContext* opCtx,
                                    bool fromMigrate) {
     const NamespaceString systemIndexes{nss.getSystemIndexesCollection()};
 
-    if (uuid && !isMasterSlave(opCtx)) {
+    if (uuid) {
         BSONObjBuilder builder;
         builder.append("createIndexes", nss.coll());
 
@@ -765,7 +757,7 @@ repl::OpTime OpObserverImpl::onRenameCollection(OperationContext* const opCtx,
     builder.append("renameCollection", fromCollection.ns());
     builder.append("to", toCollection.ns());
     builder.append("stayTemp", stayTemp);
-    if (dropTargetUUID && !isMasterSlave(opCtx)) {
+    if (dropTargetUUID) {
         dropTargetUUID->appendToBuilder(&builder, "dropTarget");
     } else {
         builder.append("dropTarget", dropTarget);
diff --git a/src/mongo/db/query/find.cpp b/src/mongo/db/query/find.cpp
index fdd402b76bd..43d86c1beab 100644
--- a/src/mongo/db/query/find.cpp
+++ b/src/mongo/db/query/find.cpp
@@ -163,8 +163,7 @@ namespace {
  *
  * Returns the number of documents in the batch in 'numResults', which must be initialized to
  * zero by the caller. Returns the final ExecState returned by the cursor in *state. Returns
- * whether or not to save the ClientCursor in 'shouldSaveCursor'. Returns the slave's time to
- * read until in 'slaveReadTill' (for master/slave).
+ * whether or not to save the ClientCursor in 'shouldSaveCursor'.
  *
  * Returns an OK status if the batch was successfully generated, and a non-OK status if the
  * PlanExecutor encounters a failure.
@@ -173,7 +172,6 @@ void generateBatch(int ntoreturn,
                    ClientCursor* cursor,
                    BufBuilder* bb,
                    int* numResults,
-                   Timestamp* slaveReadTill,
                    PlanExecutor::ExecState* state) {
     PlanExecutor* exec = cursor->getExecutor();
 
@@ -191,14 +189,6 @@ void generateBatch(int ntoreturn,
 
         // Count the result.
         (*numResults)++;
-
-        // Possibly note slave's position in the oplog.
-        if (cursor->queryOptions() & QueryOption_OplogReplay) {
-            BSONElement e = obj["ts"];
-            if (BSONType::Date == e.type() || BSONType::bsonTimestamp == e.type()) {
-                *slaveReadTill = e.timestamp();
-            }
-        }
     }
 
     // Propagate any errors to the caller.
@@ -386,11 +376,6 @@ Message getMore(OperationContext* opCtx,
         }
         opCtx->checkForInterrupt();  // May trigger maxTimeAlwaysTimeOut fail point.
 
-        cc->updateSlaveLocation(opCtx);
-
-        // If we're replaying the oplog, we save the last time that we read.
-        Timestamp slaveReadTill;
-
         // What number result are we starting at?  Used to fill out the reply.
         startingResult = cc->pos();
 
@@ -433,7 +418,7 @@ Message getMore(OperationContext* opCtx,
         PlanSummaryStats preExecutionStats;
         Explain::getSummaryStats(*exec, &preExecutionStats);
 
-        generateBatch(ntoreturn, cc, &bb, &numResults, &slaveReadTill, &state);
+        generateBatch(ntoreturn, cc, &bb, &numResults, &state);
 
         // If this is an await data cursor, and we hit EOF without generating any results, then
         // we block waiting for new data to arrive.
@@ -458,7 +443,7 @@ Message getMore(OperationContext* opCtx,
 
             // We woke up because either the timed_wait expired, or there was more data. Either
             // way, attempt to generate another batch of results.
-            generateBatch(ntoreturn, cc, &bb, &numResults, &slaveReadTill, &state);
+            generateBatch(ntoreturn, cc, &bb, &numResults, &state);
         }
 
         PlanSummaryStats postExecutionStats;
@@ -501,11 +486,6 @@ Message getMore(OperationContext* opCtx,
             LOG(5) << "getMore saving client cursor ended with state "
                    << PlanExecutor::statestr(state);
 
-            // Possibly note slave's position in the oplog.
-            if ((cc->queryOptions() & QueryOption_OplogReplay) && !slaveReadTill.isNull()) {
-                cc->slaveReadTill(slaveReadTill);
-            }
-
             *exhaust = cc->queryOptions() & QueryOption_Exhaust;
 
             // We assume that cursors created through a DBDirectClient are always used from their
@@ -633,9 +613,6 @@ std::string runQuery(OperationContext* opCtx,
     // How many results have we obtained from the executor?
     int numResults = 0;
 
-    // If we're replaying the oplog, we save the last time that we read.
-    Timestamp slaveReadTill;
-
     BSONObj obj;
     PlanExecutor::ExecState state;
 
@@ -658,14 +635,6 @@ std::string runQuery(OperationContext* opCtx,
         // Count the result.
         ++numResults;
 
-        // Possibly note slave's position in the oplog.
-        if (qr.isOplogReplay()) {
-            BSONElement e = obj["ts"];
-            if (Date == e.type() || bsonTimestamp == e.type()) {
-                slaveReadTill = e.timestamp();
-            }
-        }
-
         if (FindCommon::enoughForFirstBatch(qr, numResults)) {
             LOG(5) << "Enough for first batch, wantMore=" << qr.wantMore()
                    << " ntoreturn=" << qr.getNToReturn().value_or(0)
@@ -711,11 +680,6 @@ std::string runQuery(OperationContext* opCtx,
                << " results";
 
         // TODO document
-        if (qr.isOplogReplay() && !slaveReadTill.isNull()) {
-            pinnedCursor.getCursor()->slaveReadTill(slaveReadTill);
-        }
-
-        // TODO document
         if (qr.isExhaust()) {
             curOp.debug().exhaust = true;
         }
diff --git a/src/mongo/db/read_concern.cpp b/src/mongo/db/read_concern.cpp
index 132680d37d1..b5af878c5b8 100644
--- a/src/mongo/db/read_concern.cpp
+++ b/src/mongo/db/read_concern.cpp
@@ -212,7 +212,7 @@ Status waitForReadConcern(OperationContext* opCtx,
 
     if (readConcernArgs.getLevel() == repl::ReadConcernLevel::kLinearizableReadConcern) {
         if (replCoord->getReplicationMode() != repl::ReplicationCoordinator::modeReplSet) {
-            // For master/slave and standalone nodes, Linearizable Read is not supported.
+            // For standalone nodes, Linearizable Read is not supported.
             return {ErrorCodes::NotAReplicaSet,
                     "node needs to be a replica set member to use read concern"};
         }
diff --git a/src/mongo/db/repl/SConscript b/src/mongo/db/repl/SConscript
index 4fc00aa268e..d09428bf75d 100644
--- a/src/mongo/db/repl/SConscript
+++ b/src/mongo/db/repl/SConscript
@@ -990,7 +990,6 @@ env.Library('read_concern_args',
 
 env.Library('replica_set_messages',
             [
-                'handshake_args.cpp',
                 'is_master_response.cpp',
                 'member_config.cpp',
                 'repl_set_config.cpp',
diff --git a/src/mongo/db/repl/apply_ops.cpp b/src/mongo/db/repl/apply_ops.cpp
index 2d85fe4c908..ce59247fabb 100644
--- a/src/mongo/db/repl/apply_ops.cpp
+++ b/src/mongo/db/repl/apply_ops.cpp
@@ -443,8 +443,7 @@ Status applyOps(OperationContext* opCtx,
         writeConflictRetry(opCtx, "applyOps", dbName, [&] {
             BSONObjBuilder intermediateResult;
             std::unique_ptr<BSONArrayBuilder> opsBuilder;
-            if (opCtx->writesAreReplicated() &&
-                repl::ReplicationCoordinator::modeMasterSlave != replCoord->getReplicationMode()) {
+            if (opCtx->writesAreReplicated()) {
                 opsBuilder = stdx::make_unique<BSONArrayBuilder>();
             }
             WriteUnitOfWork wunit(opCtx);
diff --git a/src/mongo/db/repl/handshake_args.cpp b/src/mongo/db/repl/handshake_args.cpp
deleted file mode 100644
index d8ebf3c0fc7..00000000000
--- a/src/mongo/db/repl/handshake_args.cpp
+++ /dev/null
@@ -1,105 +0,0 @@
-/**
- *    Copyright 2014 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the GNU Affero General Public License in all respects for
- *    all of the code used other than as permitted herein. If you modify file(s)
- *    with this exception, you may extend this exception to your version of the
- *    file(s), but you are not obligated to do so. If you do not wish to do so,
- *    delete this exception statement from your version. If you delete this
- *    exception statement from all source files in the program, then also delete
- *    it in the license file.
- */
-
-#include "mongo/platform/basic.h"
-
-#include "mongo/db/repl/handshake_args.h"
-
-#include "mongo/base/status.h"
-#include "mongo/bson/util/bson_check.h"
-#include "mongo/bson/util/bson_extract.h"
-#include "mongo/db/jsobj.h"
-
-namespace mongo {
-namespace repl {
-
-namespace {
-
-const std::string kRIDFieldName = "handshake";
-// TODO(danneberg) remove after 3.0 since this field is only allowed for backwards compatibility
-const std::string kOldMemberConfigFieldName = "config";
-const std::string kMemberIdFieldName = "member";
-
-const std::string kLegalHandshakeFieldNames[] = {
-    kRIDFieldName, kOldMemberConfigFieldName, kMemberIdFieldName};
-
-}  // namespace
-
-HandshakeArgs::HandshakeArgs() : _hasRid(false), _hasMemberId(false), _rid(OID()), _memberId(-1) {}
-
-Status HandshakeArgs::initialize(const BSONObj& argsObj) {
-    Status status =
-        bsonCheckOnlyHasFieldsForCommand("HandshakeArgs", argsObj, kLegalHandshakeFieldNames);
-    if (!status.isOK())
-        return status;
-
-    BSONElement oid;
-    status = bsonExtractTypedField(argsObj, kRIDFieldName, jstOID, &oid);
-    if (!status.isOK())
-        return status;
-    _rid = oid.OID();
-    _hasRid = true;
-
-    status = bsonExtractIntegerField(argsObj, kMemberIdFieldName, &_memberId);
-    if (!status.isOK()) {
-        // field not necessary for master slave, do not return NoSuchKey Error
-        if (status != ErrorCodes::NoSuchKey) {
-            return status;
-        }
-        _memberId = -1;
-    } else {
-        _hasMemberId = true;
-    }
-
-    return Status::OK();
-}
-
-bool HandshakeArgs::isInitialized() const {
-    return _hasRid;
-}
-
-void HandshakeArgs::setRid(const OID& newVal) {
-    _rid = newVal;
-    _hasRid = true;
-}
-
-void HandshakeArgs::setMemberId(long long newVal) {
-    _memberId = newVal;
-    _hasMemberId = true;
-}
-
-BSONObj HandshakeArgs::toBSON() const {
-    invariant(isInitialized());
-    BSONObjBuilder builder;
-    builder.append(kRIDFieldName, _rid);
-    builder.append(kMemberIdFieldName, _memberId);
-    return builder.obj();
-}
-
-}  // namespace repl
-}  // namespace mongo
diff --git a/src/mongo/db/repl/handshake_args.h b/src/mongo/db/repl/handshake_args.h
deleted file mode 100644
index b83bef87842..00000000000
--- a/src/mongo/db/repl/handshake_args.h
+++ /dev/null
@@ -1,103 +0,0 @@
-/**
- *    Copyright (C) 2014 MongoDB Inc.
- *
- *    This program is free software: you can redistribute it and/or  modify
- *    it under the terms of the GNU Affero General Public License, version 3,
- *    as published by the Free Software Foundation.
- *
- *    This program is distributed in the hope that it will be useful,
- *    but WITHOUT ANY WARRANTY; without even the implied warranty of
- *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *    GNU Affero General Public License for more details.
- *
- *    You should have received a copy of the GNU Affero General Public License
- *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- *    As a special exception, the copyright holders give permission to link the
- *    code of portions of this program with the OpenSSL library under certain
- *    conditions as described in each individual source file and distribute
- *    linked combinations including the program with the OpenSSL library. You
- *    must comply with the GNU Affero General Public License in all respects for
- *    all of the code used other than as permitted herein. If you modify file(s)
- *    with this exception, you may extend this exception to your version of the
- *    file(s), but you are not obligated to do so. If you do not wish to do so,
- *    delete this exception statement from your version. If you delete this
- *    exception statement from all source files in the program, then also delete
- *    it in the license file.
- */
-
-#pragma once
-
-#include "mongo/db/jsobj.h"
-
-namespace mongo {
-
-class Status;
-
-namespace repl {
-
-/**
- * Arguments to the handshake command.
- */
-class HandshakeArgs {
-public:
-    HandshakeArgs();
-
-    /**
-     * Initializes this HandshakeArgs from the contents of args.
-     */
-    Status initialize(const BSONObj& argsObj);
-
-    /**
-     * Returns true if all required fields have been initialized.
-     */
-    bool isInitialized() const;
-
-    /**
-     * Gets the _id of the sender in their ReplSetConfig.
-     */
-    long long getMemberId() const {
-        return _memberId;
-    }
-
-    /**
-     * Gets the unique identifier of the sender, which is used to track replication progress.
-     */
-    OID getRid() const {
-        return _rid;
-    }
-
-    /**
-     * The below methods check whether or not value in the method name has been set.
-     */
-    bool hasRid() {
-        return _hasRid;
-    };
-    bool hasMemberId() {
-        return _hasMemberId;
-    };
-
-    /**
-     * The below methods set the value in the method name to 'newVal'.
-     */
-    void setRid(const OID& newVal);
-    void setMemberId(long long newVal);
-
-    /**
-     * Returns a BSONified version of the object.
-     * Should only be called if the mandatory fields have been set.
-     * Optional fields are only included if they have been set.
-     */
-    BSONObj toBSON() const;
-
-private:
-    bool _hasRid;
-    bool _hasMemberId;
-
-    // look at the body of the isInitialized() function to see which fields are mandatory
-    OID _rid;
-    long long _memberId;
-};
-
-}  // namespace repl
-}  // namespace mongo
diff --git a/src/mongo/db/repl/member_data.cpp b/src/mongo/db/repl/member_data.cpp
index c59eb1c6ce6..0ea383532b0 100644
--- a/src/mongo/db/repl/member_data.cpp
+++ b/src/mongo/db/repl/member_data.cpp
@@ -135,8 +135,8 @@ void MemberData::setLastDurableOpTime(OpTime opTime, Date_t now) {
         log() << "Durable progress (" << opTime << ") is ahead of the applied progress ("
               << _lastAppliedOpTime << ". This is likely due to a "
                                        "rollback."
-              << " memberid: " << _memberId << " rid: " << _rid << " host "
-              << _hostAndPort.toString() << " previous durable progress: " << _lastDurableOpTime;
+              << " memberid: " << _memberId << _hostAndPort.toString()
+              << " previous durable progress: " << _lastDurableOpTime;
     } else {
         _lastDurableOpTime = opTime;
     }
diff --git a/src/mongo/db/repl/member_data.h b/src/mongo/db/repl/member_data.h
index 9a1d56c0c5c..ab484a64469 100644
--- a/src/mongo/db/repl/member_data.h
+++ b/src/mongo/db/repl/member_data.h
@@ -131,10 +131,6 @@ public:
         return _memberId;
     }
 
-    OID getRid() const {
-        return _rid;
-    }
-
     bool isSelf() const {
         return _isSelf;
     }
@@ -229,10 +225,6 @@ public:
         _memberId = memberId;
     }
 
-    void setRid(OID rid) {
-        _rid = rid;
-    }
-
 private:
     // -1 = not checked yet, 0 = member is down/unreachable, 1 = member is up
     int _health;
@@ -275,11 +267,8 @@ private:
     // Is this the data for this member?
     bool _isSelf;
 
-    // This member's RID, used only in master/slave replication.
-    OID _rid;
-
     // This member's member ID.  memberId and hostAndPort duplicate information in the
-    // configuration for replica sets, but are required to be here for master/slave replication.
+    // set's ReplSetConfig.
     int _memberId = -1;
 
     // Client address of this member.
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index eba01f1076c..ec622e6ff1b 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -111,8 +111,6 @@ using std::vector;
 using IndexVersion = IndexDescriptor::IndexVersion;
 
 namespace repl {
-std::string masterSlaveOplogName = "local.oplog.$main";
-
 namespace {
 /**
  * The `_localOplogCollection` pointer is always valid (or null) because an
@@ -163,13 +161,9 @@ void _getNextOpTimes(OperationContext* opCtx,
 
     fassert(28560, oplog->getRecordStore()->oplogDiskLocRegister(opCtx, ts));
 
-    // Set hash if we're in replset mode, otherwise it remains 0 in master/slave.
-    const bool needHash = (replCoord->getReplicationMode() == ReplicationCoordinator::modeReplSet);
     for (std::size_t i = 0; i < count; i++) {
         slotsOut[i].opTime = {Timestamp(ts.asULL() + i), term};
-        if (needHash) {
-            slotsOut[i].hash = hashGenerator.nextInt64();
-        }
+        slotsOut[i].hash = hashGenerator.nextInt64();
     }
 }
 
@@ -218,14 +212,9 @@ void setOplogCollectionName(ServiceContext* service) {
         case ReplicationCoordinator::modeReplSet:
             _oplogCollectionName = NamespaceString::kRsOplogNamespace.ns();
             break;
-        case ReplicationCoordinator::modeMasterSlave:
-            _oplogCollectionName = masterSlaveOplogName;
-            break;
         case ReplicationCoordinator::modeNone:
             // leave empty.
             break;
-        default:
-            MONGO_UNREACHABLE;
     }
 }
 
@@ -332,9 +321,7 @@ OplogDocWriter _logOpWriter(OperationContext* opCtx,
     b.append("v", OplogEntry::kOplogVersion);
     b.append("op", opstr);
     b.append("ns", nss.ns());
-    if (uuid &&
-        ReplicationCoordinator::get(opCtx)->getReplicationMode() !=
-            ReplicationCoordinator::modeMasterSlave)
+    if (uuid)
         uuid->appendToBuilder(&b, "ui");
 
     if (fromMigrate)
@@ -361,7 +348,6 @@ OplogDocWriter _logOpWriter(OperationContext* opCtx,
     "u" update
     "d" delete
     "c" db cmd
-    "db" declares presence of a database (ns is set to the db name + '.') (master/slave only)
     "n" no op
 */
 
@@ -370,8 +356,7 @@ OplogDocWriter _logOpWriter(OperationContext* opCtx,
  * writers - an array with size nDocs of DocWriter objects.
  * timestamps - an array with size nDocs of respective Timestamp objects for each DocWriter.
  * oplogCollection - collection to be written to.
- * replicationMode - ReplSet or MasterSlave.
- * finalOpTime - the OpTime of the last DocWriter object.
+  * finalOpTime - the OpTime of the last DocWriter object.
  */
 void _logOpsInner(OperationContext* opCtx,
                   const NamespaceString& nss,
@@ -1139,10 +1124,6 @@ Status applyOperation_inlock(OperationContext* opCtx,
                     // We do not assign timestamps on standalones.
                     return false;
                 }
-                case ReplicationCoordinator::modeMasterSlave: {
-                    // Master-slave does not support timestamps so we do not assign a timestamp.
-                    return false;
-                }
             }
         }
         return true;
@@ -1549,10 +1530,6 @@ Status applyCommand_inlock(OperationContext* opCtx,
                     // We do not assign timestamps on standalones.
                     return false;
                 }
-                case ReplicationCoordinator::modeMasterSlave: {
-                    // Master-slave does not support timestamps so we do not assign a timestamp.
-                    return false;
-                }
             }
             MONGO_UNREACHABLE;
         }
@@ -1605,11 +1582,7 @@ Status applyCommand_inlock(OperationContext* opCtx,
                 break;
             }
             default:
-                if (_oplogCollectionName == masterSlaveOplogName) {
-                    error() << "Failed command " << redact(o) << " on " << nss.db()
-                            << " with status " << status << " during oplog application";
-                } else if (curOpToApply.acceptableErrors.find(status.code()) ==
-                           curOpToApply.acceptableErrors.end()) {
+                if (!curOpToApply.acceptableErrors.count(status.code())) {
                     error() << "Failed command " << redact(o) << " on " << nss.db()
                             << " with status " << status << " during oplog application";
                     return status;
diff --git a/src/mongo/db/repl/oplog.h b/src/mongo/db/repl/oplog.h
index 1120b96c152..3658bb8bbb0 100644
--- a/src/mongo/db/repl/oplog.h
+++ b/src/mongo/db/repl/oplog.h
@@ -95,10 +95,6 @@ void createOplog(OperationContext* opCtx, const std::string& oplogCollectionName
  */
 void createOplog(OperationContext* opCtx);
 
-extern std::string masterSlaveOplogName;
-
-extern int OPLOG_VERSION;
-
 /**
  * Log insert(s) to the local oplog.
  * Returns the OpTime of every insert.
diff --git a/src/mongo/db/repl/oplogreader.cpp b/src/mongo/db/repl/oplogreader.cpp
index 9f5f01021bf..b65de6946ed 100644
--- a/src/mongo/db/repl/oplogreader.cpp
+++ b/src/mongo/db/repl/oplogreader.cpp
@@ -66,9 +66,6 @@ OplogReader::OplogReader() {
 
     /* TODO: slaveOk maybe shouldn't use? */
     _tailingQueryOptions |= QueryOption_AwaitData;
-
-    // Currently find command doesn't do the cursor tracking that master-slave relies on.
-    _tailingQueryOptions |= DBClientCursor::QueryOptionLocal_forceOpQuery;
 }
 
 bool OplogReader::connect(const HostAndPort& host) {
diff --git a/src/mongo/db/repl/oplogreader.h b/src/mongo/db/repl/oplogreader.h
index 92e224a6498..335771de867 100644
--- a/src/mongo/db/repl/oplogreader.h
+++ b/src/mongo/db/repl/oplogreader.h
@@ -109,17 +109,6 @@ public:
     BSONObj nextSafe() {
         return cursor->nextSafe();
     }
-
-    // master/slave only
-    void peek(std::vector<BSONObj>& v, int n) {
-        if (cursor.get())
-            cursor->peek(v, n);
-    }
-
-    // master/slave only
-    void putBack(BSONObj op) {
-        cursor->putBack(op);
-    }
 };
 
 }  // namespace repl
diff --git a/src/mongo/db/repl/repl_client_info.h b/src/mongo/db/repl/repl_client_info.h
index 09fc70f5a42..d27d7bd370b 100644
--- a/src/mongo/db/repl/repl_client_info.h
+++ b/src/mongo/db/repl/repl_client_info.h
@@ -56,14 +56,6 @@ public:
         _lastOp = OpTime();
     }
 
-    // Only used for master/slave
-    void setRemoteID(OID rid) {
-        _remoteId = rid;
-    }
-    OID getRemoteID() const {
-        return _remoteId;
-    }
-
     /**
      * Use this to set the LastOp to the latest known OpTime in the oplog.
      * This is necessary when doing no-op writes, as we need to set the client's lastOp to a proper
@@ -75,7 +67,6 @@ private:
     static const long long kUninitializedTerm = -1;
 
     OpTime _lastOp = OpTime();
-    OID _remoteId = OID();
 };
 
 }  // namespace repl
diff --git a/src/mongo/db/repl/replication_coordinator.h b/src/mongo/db/repl/replication_coordinator.h
index 96be0d7be59..f43c285807c 100644
--- a/src/mongo/db/repl/replication_coordinator.h
+++ b/src/mongo/db/repl/replication_coordinator.h
@@ -65,7 +65,6 @@ class ReplSetMetadata;
 namespace repl {
 
 class BackgroundSync;
-class HandshakeArgs;
 class IsMasterResponse;
 class OplogReader;
 class OpTime;
@@ -124,17 +123,16 @@ public:
      */
     virtual const ReplSettings& getSettings() const = 0;
 
-    enum Mode { modeNone = 0, modeReplSet, modeMasterSlave };
+    enum Mode { modeNone = 0, modeReplSet };
 
     /**
-     * Returns a value indicating whether this node was configured at start-up to run
-     * standalone, as part of a master-slave pair, or as a member of a replica set.
+     * Returns a value indicating whether this node was configured at start-up to run standalone or
+     * as a member of a replica set.
      */
     virtual Mode getReplicationMode() const = 0;
 
     /**
-     * Returns true if this node is configured to be a member of a replica set or master/slave
-     * setup.
+     * Returns true if this node is configured to be a member of a replica set.
      */
     virtual bool isReplEnabled() const = 0;
 
@@ -209,9 +207,8 @@ public:
     virtual bool isMasterForReportingPurposes() = 0;
 
     /**
-     * Returns true if it is valid for this node to accept writes on the given database.
-     * Currently this is true only if this node is Primary, master in master/slave,
-     * a standalone, or is writing to the local database.
+     * Returns true if it is valid for this node to accept writes on the given database.  Currently
+     * this is true only if this node is Primary, a standalone, or is writing to the local database.
      *
      * If a node was started with the replSet argument, but has not yet received a config, it
      * will not be able to receive writes to a database other than local (it will not be
@@ -282,12 +279,6 @@ public:
                                              const NamespaceString& ns) = 0;
 
     /**
-     * Updates our internal tracking of the last OpTime applied for the given slave
-     * identified by "rid".  Only valid to call in master/slave mode
-     */
-    virtual Status setLastOptimeForSlave(const OID& rid, const Timestamp& ts) = 0;
-
-    /**
      * Updates our internal tracking of the last OpTime applied to this node.
      *
      * The new value of "opTime" must be no less than any prior value passed to this method, and
@@ -388,12 +379,6 @@ public:
     virtual OID getElectionId() = 0;
 
     /**
-     * Returns the RID for this node.  The RID is used to identify this node to our sync source
-     * when sending updates about our replication progress.
-     */
-    virtual OID getMyRID() const = 0;
-
-    /**
      * Returns the id for this node as specified in the current replica set configuration.
      */
     virtual int getMyId() const = 0;
@@ -525,7 +510,7 @@ public:
 
     /**
      * Handles an incoming isMaster command for a replica set node.  Should not be
-     * called on a master-slave or standalone node.
+     * called on a standalone node.
      */
     virtual void fillIsMasterForReplSet(IsMasterResponse* result) = 0;
 
@@ -681,16 +666,6 @@ public:
                                                 long long* configVersion) = 0;
 
     /**
-     * Handles an incoming Handshake command. Associates the node's 'remoteID' with its
-     * 'handshake' object. This association is used to update internal representation of
-     * replication progress and to forward the node's replication progress upstream when this
-     * node is being chained through in master/slave replication.
-     *
-     * Returns ErrorCodes::IllegalOperation if we're not running with master/slave replication.
-     */
-    virtual Status processHandshake(OperationContext* opCtx, const HandshakeArgs& handshake) = 0;
-
-    /**
      * Returns a bool indicating whether or not this node builds indexes.
      */
     virtual bool buildsIndexes() = 0;
diff --git a/src/mongo/db/repl/replication_coordinator_external_state.h b/src/mongo/db/repl/replication_coordinator_external_state.h
index 38697e94c1c..5ad47f2cbcb 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state.h
+++ b/src/mongo/db/repl/replication_coordinator_external_state.h
@@ -85,8 +85,6 @@ public:
 
     /**
      * Starts steady state sync for replica set member.
-     *
-     * NOTE: Use either this or the Master/Slave version, but not both.
      */
     virtual void startSteadyStateReplication(OperationContext* opCtx,
                                              ReplicationCoordinator* replCoord) = 0;
@@ -160,14 +158,6 @@ public:
     virtual void forwardSlaveProgress() = 0;
 
     /**
-     * Queries the singleton document in local.me.  If it exists and our hostname has not
-     * changed since we wrote, returns the RID stored in the object.  If the document does not
-     * exist or our hostname doesn't match what was recorded in local.me, generates a new OID
-     * to use as our RID, stores it in local.me, and returns it.
-     */
-    virtual OID ensureMe(OperationContext*) = 0;
-
-    /**
      * Returns true if "host" is one of the network identities of this node.
      */
     virtual bool isSelf(const HostAndPort& host, ServiceContext* service) = 0;
diff --git a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
index d5baf0d959b..79195384543 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_external_state_impl.cpp
@@ -490,34 +490,6 @@ void ReplicationCoordinatorExternalStateImpl::forwardSlaveProgress() {
     _syncSourceFeedback.forwardSlaveProgress();
 }
 
-OID ReplicationCoordinatorExternalStateImpl::ensureMe(OperationContext* opCtx) {
-    std::string myname = getHostName();
-    OID myRID;
-    {
-        Lock::DBLock lock(opCtx, meDatabaseName, MODE_X);
-
-        BSONObj me;
-        // local.me is an identifier for a server for getLastError w:2+
-        // TODO: handle WriteConflictExceptions below
-        if (!Helpers::getSingleton(opCtx, meCollectionName, me) || !me.hasField("host") ||
-            me["host"].String() != myname) {
-            myRID = OID::gen();
-
-            // clean out local.me
-            Helpers::emptyCollection(opCtx, NamespaceString(meCollectionName));
-
-            // repopulate
-            BSONObjBuilder b;
-            b.append("_id", myRID);
-            b.append("host", myname);
-            Helpers::putSingleton(opCtx, meCollectionName, b.done());
-        } else {
-            myRID = me["_id"].OID();
-        }
-    }
-    return myRID;
-}
-
 StatusWith<BSONObj> ReplicationCoordinatorExternalStateImpl::loadLocalConfigDocument(
     OperationContext* opCtx) {
     try {
diff --git a/src/mongo/db/repl/replication_coordinator_external_state_impl.h b/src/mongo/db/repl/replication_coordinator_external_state_impl.h
index 3d124a24ef2..b3ed7827dde 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_impl.h
+++ b/src/mongo/db/repl/replication_coordinator_external_state_impl.h
@@ -83,7 +83,6 @@ public:
     void onDrainComplete(OperationContext* opCtx) override;
     OpTime onTransitionToPrimary(OperationContext* opCtx, bool isV1ElectionProtocol) override;
     virtual void forwardSlaveProgress();
-    virtual OID ensureMe(OperationContext* opCtx);
     virtual bool isSelf(const HostAndPort& host, ServiceContext* service);
     virtual StatusWith<BSONObj> loadLocalConfigDocument(OperationContext* opCtx);
     virtual Status storeLocalConfigDocument(OperationContext* opCtx, const BSONObj& config);
diff --git a/src/mongo/db/repl/replication_coordinator_external_state_mock.cpp b/src/mongo/db/repl/replication_coordinator_external_state_mock.cpp
index 5f88d85e0ec..f6c0104283f 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_mock.cpp
+++ b/src/mongo/db/repl/replication_coordinator_external_state_mock.cpp
@@ -96,10 +96,6 @@ ThreadPool* ReplicationCoordinatorExternalStateMock::getDbWorkThreadPool() const
 
 void ReplicationCoordinatorExternalStateMock::forwardSlaveProgress() {}
 
-OID ReplicationCoordinatorExternalStateMock::ensureMe(OperationContext*) {
-    return OID::gen();
-}
-
 bool ReplicationCoordinatorExternalStateMock::isSelf(const HostAndPort& host,
                                                      ServiceContext* const service) {
     return sequenceContains(_selfHosts, host);
diff --git a/src/mongo/db/repl/replication_coordinator_external_state_mock.h b/src/mongo/db/repl/replication_coordinator_external_state_mock.h
index 2d7f5563bba..c45fd82329d 100644
--- a/src/mongo/db/repl/replication_coordinator_external_state_mock.h
+++ b/src/mongo/db/repl/replication_coordinator_external_state_mock.h
@@ -71,7 +71,6 @@ public:
     void onDrainComplete(OperationContext* opCtx) override;
     OpTime onTransitionToPrimary(OperationContext* opCtx, bool isV1ElectionProtocol) override;
     virtual void forwardSlaveProgress();
-    virtual OID ensureMe(OperationContext*);
     virtual bool isSelf(const HostAndPort& host, ServiceContext* service);
     virtual HostAndPort getClientHostAndPort(const OperationContext* opCtx);
     virtual StatusWith<BSONObj> loadLocalConfigDocument(OperationContext* opCtx);
diff --git a/src/mongo/db/repl/replication_coordinator_impl.cpp b/src/mongo/db/repl/replication_coordinator_impl.cpp
index a9106e56cf5..cef2f6d9e2c 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl.cpp
@@ -48,7 +48,6 @@
 #include "mongo/db/repl/data_replicator_external_state_initial_sync.h"
 #include "mongo/db/repl/elect_cmd_runner.h"
 #include "mongo/db/repl/freshness_checker.h"
-#include "mongo/db/repl/handshake_args.h"
 #include "mongo/db/repl/is_master_response.h"
 #include "mongo/db/repl/last_vote.h"
 #include "mongo/db/repl/read_concern_args.h"
@@ -736,23 +735,15 @@ void ReplicationCoordinatorImpl::startup(OperationContext* opCtx) {
     invariant(_settings.usingReplSets());
 
     {
-        OID rid = _externalState->ensureMe(opCtx);
-
         stdx::lock_guard<stdx::mutex> lk(_mutex);
         fassert(18822, !_inShutdown);
         _setConfigState_inlock(kConfigStartingUp);
-        _myRID = rid;
-        _topCoord->setMyRid(rid);
-    }
-
-    _replExecutor->startup();
-
-    {
-        stdx::lock_guard<stdx::mutex> lk(_mutex);
         _topCoord->setStorageEngineSupportsReadCommitted(
             _externalState->isReadCommittedSupportedByStorageEngine(opCtx));
     }
 
+    _replExecutor->startup();
+
     bool doneLoadingConfig = _startLoadLocalConfig(opCtx);
     if (doneLoadingConfig) {
         // If we're not done loading the config, then the config state will be set by
@@ -1015,16 +1006,6 @@ void ReplicationCoordinatorImpl::signalUpstreamUpdater() {
     _externalState->forwardSlaveProgress();
 }
 
-Status ReplicationCoordinatorImpl::setLastOptimeForSlave(const OID& rid, const Timestamp& ts) {
-    stdx::unique_lock<stdx::mutex> lock(_mutex);
-
-    // term == -1 for master-slave
-    OpTime opTime(ts, OpTime::kUninitializedTerm);
-    _topCoord->setLastOptimeForSlave(rid, opTime, _replExecutor->now());
-    _updateLastCommittedOpTime_inlock();
-    return Status::OK();
-}
-
 void ReplicationCoordinatorImpl::setMyHeartbeatMessage(const std::string& msg) {
     stdx::unique_lock<stdx::mutex> lock(_mutex);
     _topCoord->setMyHeartbeatMessage(_replExecutor->now(), msg);
@@ -1462,11 +1443,6 @@ Status ReplicationCoordinatorImpl::_awaitReplication_inlock(
         return Status::OK();
     }
 
-    if (replMode == modeMasterSlave && writeConcern.wMode == WriteConcernOptions::kMajority) {
-        // with master/slave, majority is equivalent to w=1
-        return Status::OK();
-    }
-
     if (opTime.isNull()) {
         // If waiting for the empty optime, always say it's been replicated.
         return Status::OK();
@@ -1838,9 +1814,6 @@ Status ReplicationCoordinatorImpl::checkCanServeReadsFor_UNSAFE(OperationContext
     if (canAcceptWritesFor_UNSAFE(opCtx, ns)) {
         return Status::OK();
     }
-    if (getReplicationMode() == modeMasterSlave) {
-        return Status::OK();
-    }
     if (slaveOk) {
         if (isPrimaryOrSecondary) {
             return Status::OK();
@@ -1865,15 +1838,6 @@ OID ReplicationCoordinatorImpl::getElectionId() {
     return _electionId;
 }
 
-OID ReplicationCoordinatorImpl::getMyRID() const {
-    stdx::lock_guard<stdx::mutex> lock(_mutex);
-    return _getMyRID_inlock();
-}
-
-OID ReplicationCoordinatorImpl::_getMyRID_inlock() const {
-    return _myRID;
-}
-
 int ReplicationCoordinatorImpl::getMyId() const {
     stdx::lock_guard<stdx::mutex> lock(_mutex);
     return _getMyId_inlock();
@@ -2834,14 +2798,6 @@ Status ReplicationCoordinatorImpl::processReplSetUpdatePosition(const UpdatePosi
     return status;
 }
 
-Status ReplicationCoordinatorImpl::processHandshake(OperationContext* opCtx,
-                                                    const HandshakeArgs& handshake) {
-    LOG(2) << "Received handshake " << handshake.toBSON();
-    stdx::lock_guard<stdx::mutex> lock(_mutex);
-    return _topCoord->processHandshake(handshake.getRid(),
-                                       _externalState->getClientHostAndPort(opCtx));
-}
-
 bool ReplicationCoordinatorImpl::buildsIndexes() {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
     if (_selfIndex == -1) {
@@ -2854,9 +2810,7 @@ bool ReplicationCoordinatorImpl::buildsIndexes() {
 std::vector<HostAndPort> ReplicationCoordinatorImpl::getHostsWrittenTo(const OpTime& op,
                                                                        bool durablyWritten) {
     stdx::lock_guard<stdx::mutex> lk(_mutex);
-    /* skip self in master-slave mode because our own HostAndPort is unknown */
-    const bool skipSelf = getReplicationMode() == modeMasterSlave;
-    return _topCoord->getHostsWrittenTo(op, durablyWritten, skipSelf);
+    return _topCoord->getHostsWrittenTo(op, durablyWritten);
 }
 
 std::vector<HostAndPort> ReplicationCoordinatorImpl::getOtherNodesInReplSet() const {
@@ -2890,15 +2844,6 @@ Status ReplicationCoordinatorImpl::_checkIfWriteConcernCanBeSatisfied_inlock(
                       "No replication enabled when checking if write concern can be satisfied");
     }
 
-    if (getReplicationMode() == modeMasterSlave) {
-        if (!writeConcern.wMode.empty()) {
-            return Status(ErrorCodes::UnknownReplWriteConcern,
-                          "Cannot use named write concern modes in master-slave");
-        }
-        // No way to know how many slaves there are, so assume any numeric mode is possible.
-        return Status::OK();
-    }
-
     invariant(getReplicationMode() == modeReplSet);
     return _rsConfig.checkIfWriteConcernCanBeSatisfied(writeConcern);
 }
diff --git a/src/mongo/db/repl/replication_coordinator_impl.h b/src/mongo/db/repl/replication_coordinator_impl.h
index 4dbf0dd321d..d62bf217071 100644
--- a/src/mongo/db/repl/replication_coordinator_impl.h
+++ b/src/mongo/db/repl/replication_coordinator_impl.h
@@ -72,7 +72,6 @@ namespace repl {
 
 class ElectCmdRunner;
 class FreshnessChecker;
-class HandshakeArgs;
 class HeartbeatResponseAction;
 class LastVote;
 class OplogReader;
@@ -146,8 +145,6 @@ public:
 
     virtual bool shouldRelaxIndexConstraints(OperationContext* opCtx, const NamespaceString& ns);
 
-    virtual Status setLastOptimeForSlave(const OID& rid, const Timestamp& ts);
-
     virtual void setMyLastAppliedOpTime(const OpTime& opTime);
     virtual void setMyLastDurableOpTime(const OpTime& opTime);
 
@@ -170,8 +167,6 @@ public:
 
     virtual OID getElectionId() override;
 
-    virtual OID getMyRID() const override;
-
     virtual int getMyId() const override;
 
     virtual Status setFollowerMode(const MemberState& newState) override;
@@ -236,9 +231,6 @@ public:
     virtual Status processReplSetUpdatePosition(const UpdatePositionArgs& updates,
                                                 long long* configVersion) override;
 
-    virtual Status processHandshake(OperationContext* opCtx,
-                                    const HandshakeArgs& handshake) override;
-
     virtual bool buildsIndexes() override;
 
     virtual std::vector<HostAndPort> getHostsWrittenTo(const OpTime& op,
@@ -634,8 +626,6 @@ private:
 
     bool _canAcceptWritesFor_inlock(const NamespaceString& ns);
 
-    OID _getMyRID_inlock() const;
-
     int _getMyId_inlock() const;
 
     OpTime _getMyLastAppliedOpTime_inlock() const;
@@ -1165,10 +1155,6 @@ private:
     // Pointer to the ReplicationCoordinatorExternalState owned by this ReplicationCoordinator.
     std::unique_ptr<ReplicationCoordinatorExternalState> _externalState;  // (PS)
 
-    // Our RID, used to identify us to our sync source when sending replication progress
-    // updates upstream.  Set once in startReplication() and then never modified again.
-    OID _myRID;  // (M)
-
     // list of information about clients waiting on replication.  Does *not* own the WaiterInfos.
     WaiterList _replicationWaiterList;  // (M)
 
@@ -1235,7 +1221,7 @@ private:
 
     // Flag that indicates whether writes to databases other than "local" are allowed.  Used to
     // answer canAcceptWritesForDatabase() and canAcceptWritesFor() questions.
-    // Always true for standalone nodes and masters in master-slave relationships.
+    // Always true for standalone nodes.
     bool _canAcceptNonLocalWrites;  // (GM)
 
     // Flag that indicates whether reads from databases other than "local" are allowed.  Unlike
diff --git a/src/mongo/db/repl/replication_coordinator_impl_test.cpp b/src/mongo/db/repl/replication_coordinator_impl_test.cpp
index c981c0af10f..bd9f1dd9ec3 100644
--- a/src/mongo/db/repl/replication_coordinator_impl_test.cpp
+++ b/src/mongo/db/repl/replication_coordinator_impl_test.cpp
@@ -39,7 +39,6 @@
 #include "mongo/bson/util/bson_extract.h"
 #include "mongo/db/operation_context_noop.h"
 #include "mongo/db/repl/bson_extract_optime.h"
-#include "mongo/db/repl/handshake_args.h"
 #include "mongo/db/repl/is_master_response.h"
 #include "mongo/db/repl/optime.h"
 #include "mongo/db/repl/read_concern_args.h"
@@ -1375,7 +1374,6 @@ protected:
         exitNetwork();
     }
 
-    OID myRid;
     OID rid2;
     OID rid3;
 
@@ -1396,7 +1394,6 @@ private:
                                                             << "test3:1234"))),
                            HostAndPort("test1", 1234));
         ASSERT_OK(getReplCoord()->setFollowerMode(MemberState::RS_SECONDARY));
-        myRid = getReplCoord()->getMyRID();
     }
 };
 
@@ -1729,7 +1726,6 @@ private:
                                                             << "test5:1234"))),
                            HostAndPort("test1", 1234));
         ASSERT_OK(getReplCoord()->setFollowerMode(MemberState::RS_SECONDARY));
-        myRid = getReplCoord()->getMyRID();
     }
 };
 
diff --git a/src/mongo/db/repl/replication_coordinator_mock.cpp b/src/mongo/db/repl/replication_coordinator_mock.cpp
index bbc70047e36..5ff484259b4 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.cpp
+++ b/src/mongo/db/repl/replication_coordinator_mock.cpp
@@ -175,10 +175,6 @@ bool ReplicationCoordinatorMock::shouldRelaxIndexConstraints(OperationContext* o
     return !canAcceptWritesFor(opCtx, ns);
 }
 
-Status ReplicationCoordinatorMock::setLastOptimeForSlave(const OID& rid, const Timestamp& ts) {
-    return Status::OK();
-}
-
 void ReplicationCoordinatorMock::setMyHeartbeatMessage(const std::string& msg) {
     // TODO
 }
@@ -358,11 +354,6 @@ Status ReplicationCoordinatorMock::processReplSetUpdatePosition(const UpdatePosi
     return Status::OK();
 }
 
-Status ReplicationCoordinatorMock::processHandshake(OperationContext* opCtx,
-                                                    const HandshakeArgs& handshake) {
-    return Status::OK();
-}
-
 bool ReplicationCoordinatorMock::buildsIndexes() {
     // TODO
     return true;
diff --git a/src/mongo/db/repl/replication_coordinator_mock.h b/src/mongo/db/repl/replication_coordinator_mock.h
index afcb5daf6df..1151f731893 100644
--- a/src/mongo/db/repl/replication_coordinator_mock.h
+++ b/src/mongo/db/repl/replication_coordinator_mock.h
@@ -111,8 +111,6 @@ public:
 
     virtual bool shouldRelaxIndexConstraints(OperationContext* opCtx, const NamespaceString& ns);
 
-    virtual Status setLastOptimeForSlave(const OID& rid, const Timestamp& ts);
-
     virtual void setMyLastAppliedOpTime(const OpTime& opTime);
     virtual void setMyLastDurableOpTime(const OpTime& opTime);
 
@@ -198,8 +196,6 @@ public:
     virtual Status processReplSetUpdatePosition(const UpdatePositionArgs& updates,
                                                 long long* configVersion);
 
-    virtual Status processHandshake(OperationContext* opCtx, const HandshakeArgs& handshake);
-
     virtual bool buildsIndexes();
 
     virtual std::vector<HostAndPort> getHostsWrittenTo(const OpTime& op, bool durablyWritten);
diff --git a/src/mongo/db/repl/replication_info.cpp b/src/mongo/db/repl/replication_info.cpp
index 7ee9664690e..bed3b9aeca2 100644
--- a/src/mongo/db/repl/replication_info.cpp
+++ b/src/mongo/db/repl/replication_info.cpp
@@ -198,14 +198,10 @@ public:
         // TODO(siyuan) Output term of OpTime
         result.append("latestOptime", replCoord->getMyLastAppliedOpTime().getTimestamp());
 
-        const std::string& oplogNS =
-            replCoord->getReplicationMode() == ReplicationCoordinator::modeReplSet
-            ? NamespaceString::kRsOplogNamespace.ns()
-            : masterSlaveOplogName;
         BSONObj o;
         uassert(17347,
                 "Problem reading earliest entry from oplog",
-                Helpers::getSingleton(opCtx, oplogNS.c_str(), o));
+                Helpers::getSingleton(opCtx, NamespaceString::kRsOplogNamespace.ns().c_str(), o));
         result.append("earliestOptime", o["ts"].timestamp());
         return result.obj();
     }
@@ -220,8 +216,7 @@ public:
         return AllowedOnSecondary::kAlways;
     }
     std::string help() const override {
-        return "Check if this server is primary for a replica pair/set; also if it is --master or "
-               "--slave in simple master/slave setups.\n"
+        return "Check if this server is primary for a replica set\n"
                "{ isMaster : 1 }";
     }
     virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
diff --git a/src/mongo/db/repl/topology_coordinator.cpp b/src/mongo/db/repl/topology_coordinator.cpp
index a8eba4a89d2..b5f763f56d2 100644
--- a/src/mongo/db/repl/topology_coordinator.cpp
+++ b/src/mongo/db/repl/topology_coordinator.cpp
@@ -40,7 +40,6 @@
 #include "mongo/db/client.h"
 #include "mongo/db/mongod_options.h"
 #include "mongo/db/operation_context.h"
-#include "mongo/db/repl/handshake_args.h"
 #include "mongo/db/repl/heartbeat_response_action.h"
 #include "mongo/db/repl/is_master_response.h"
 #include "mongo/db/repl/isself.h"
@@ -1194,14 +1193,9 @@ HeartbeatResponseAction TopologyCoordinator::checkMemberTimeouts(Date_t now) {
 }
 
 std::vector<HostAndPort> TopologyCoordinator::getHostsWrittenTo(const OpTime& op,
-                                                                bool durablyWritten,
-                                                                bool skipSelf) {
+                                                                bool durablyWritten) {
     std::vector<HostAndPort> hosts;
     for (const auto& memberData : _memberData) {
-        if (skipSelf && memberData.isSelf()) {
-            continue;
-        }
-
         if (durablyWritten) {
             if (memberData.getLastDurableOpTime() < op) {
                 continue;
@@ -1350,28 +1344,6 @@ StatusWith<bool> TopologyCoordinator::setLastOptime(const UpdatePositionArgs::Up
     return advancedOpTime;
 }
 
-void TopologyCoordinator::setLastOptimeForSlave(const OID& rid, const OpTime& opTime, Date_t now) {
-    massert(28576,
-            "Received an old style replication progress update, which is only used for Master/"
-            "Slave replication now, but this node is not using Master/Slave replication. "
-            "This is likely caused by an old (pre-2.6) member syncing from this node.",
-            !_rsConfig.isInitialized());
-    auto* memberData = _findMemberDataByRid(rid);
-    if (memberData) {
-        memberData->advanceLastAppliedOpTime(opTime, now);
-    } else {
-        invariant(!_memberData.empty());  // Must always have our own entry first.
-        _memberData.emplace_back();
-        memberData = &_memberData.back();
-        memberData->setRid(rid);
-        memberData->setLastAppliedOpTime(opTime, now);
-    }
-}
-
-void TopologyCoordinator::setMyRid(const OID& rid) {
-    _selfMemberData().setRid(rid);
-}
-
 MemberData* TopologyCoordinator::_findMemberDataByMemberId(const int memberId) {
     const int memberIndex = _getMemberIndex(memberId);
     if (memberIndex >= 0)
@@ -1379,30 +1351,6 @@ MemberData* TopologyCoordinator::_findMemberDataByMemberId(const int memberId) {
     return nullptr;
 }
 
-MemberData* TopologyCoordinator::_findMemberDataByRid(const OID rid) {
-    for (auto& memberData : _memberData) {
-        if (memberData.getRid() == rid)
-            return &memberData;
-    }
-    return nullptr;
-}
-
-Status TopologyCoordinator::processHandshake(const OID& rid, const HostAndPort& hostAndPort) {
-    if (_rsConfig.isInitialized()) {
-        return Status(ErrorCodes::IllegalOperation,
-                      "The handshake command is only used for master/slave replication");
-    }
-    auto* memberData = _findMemberDataByRid(rid);
-    if (!memberData) {
-        invariant(!_memberData.empty());  // Must always have our own entry first.
-        _memberData.emplace_back();
-        auto& newMember = _memberData.back();
-        newMember.setRid(rid);
-        newMember.setHostAndPort(hostAndPort);
-    }
-    return Status::OK();
-}
-
 HeartbeatResponseAction TopologyCoordinator::_updatePrimaryFromHBDataV1(
     int updatedConfigIndex, const MemberState& originalState, Date_t now) {
     //
@@ -2206,7 +2154,6 @@ void TopologyCoordinator::fillMemberData(BSONObjBuilder* result) {
     {
         for (const auto& memberData : _memberData) {
             BSONObjBuilder entry(replicationProgress.subobjStart());
-            entry.append("rid", memberData.getRid());
             const auto lastDurableOpTime = memberData.getLastDurableOpTime();
             if (_rsConfig.getProtocolVersion() == 1) {
                 BSONObjBuilder opTime(entry.subobjStart("optime"));
@@ -2489,8 +2436,8 @@ const int TopologyCoordinator::_selfMemberDataIndex() const {
     invariant(!_memberData.empty());
     if (_selfIndex >= 0)
         return _selfIndex;
-    // In master-slave mode, the first entry is for self.  If there is no config
-    // or we're not in the config, the first-and-only entry should be for self.
+    // If there is no config or we're not in the config, the first-and-only entry should be for
+    // self.
     return 0;
 }
 
diff --git a/src/mongo/db/repl/topology_coordinator.h b/src/mongo/db/repl/topology_coordinator.h
index b23f0967922..306a2e896c3 100644
--- a/src/mongo/db/repl/topology_coordinator.h
+++ b/src/mongo/db/repl/topology_coordinator.h
@@ -472,9 +472,7 @@ public:
      * "durablyWritten" indicates whether the operation has to be durably applied.
      * "skipSelf" means to exclude this node whether or not the op has been applied.
      */
-    std::vector<HostAndPort> getHostsWrittenTo(const OpTime& op,
-                                               bool durablyWritten,
-                                               bool skipSelf);
+    std::vector<HostAndPort> getHostsWrittenTo(const OpTime& op, bool durablyWritten);
 
     /**
      * Marks a member as down from our perspective and returns a bool which indicates if we can no
@@ -543,26 +541,6 @@ public:
     StatusWith<bool> setLastOptime(const UpdatePositionArgs::UpdateInfo& args,
                                    Date_t now,
                                    long long* configVersion);
-    /*
-     * Sets the last optimes for a slave node.
-     *
-     * Used only in master/slave replication.
-     */
-
-    void setLastOptimeForSlave(const OID& rid, const OpTime& opTime, Date_t now);
-
-    /*
-     * Set the RID for this node.
-     *
-     * Used only in master/slave replication.
-     */
-    void setMyRid(const OID& rid);
-
-    /**
-     * Process a handshake command, adding the slave to the member list if it isn't already there.
-     * Used only in master/slave mode
-     */
-    Status processHandshake(const OID& rid, const HostAndPort& hostAndPort);
 
     /**
      * If getRole() == Role::candidate and this node has not voted too recently, updates the
@@ -876,13 +854,6 @@ private:
      */
     MemberData* _findMemberDataByMemberId(const int memberId);
 
-    /*
-     * Returns information we have on the state of the node identified by rid.  Returns
-     * nullptr if rid is not found in the heartbeat data.  This method is used only for
-     * master/slave replication.
-     */
-    MemberData* _findMemberDataByRid(const OID rid);
-
     // Returns NULL if there is no primary, or the MemberConfig* for the current primary
     const MemberConfig* _currentPrimaryMember() const;
 
diff --git a/src/mongo/db/s/chunk_move_write_concern_options.cpp b/src/mongo/db/s/chunk_move_write_concern_options.cpp
index 7cccc644789..f9d6095229f 100644
--- a/src/mongo/db/s/chunk_move_write_concern_options.cpp
+++ b/src/mongo/db/s/chunk_move_write_concern_options.cpp
@@ -87,14 +87,6 @@ StatusWith<WriteConcernOptions> ChunkMoveWriteConcernOptions::getEffectiveWriteC
 
         repl::ReplicationCoordinator* replCoordinator = repl::ReplicationCoordinator::get(opCtx);
 
-        if (replCoordinator->getReplicationMode() ==
-                repl::ReplicationCoordinator::modeMasterSlave &&
-            writeConcern.shouldWaitForOtherNodes()) {
-            warning() << "moveChunk cannot check if secondary throttle setting "
-                      << writeConcern.toBSON()
-                      << " can be enforced in a master slave configuration";
-        }
-
         Status status = replCoordinator->checkIfWriteConcernCanBeSatisfied(writeConcern);
         if (!status.isOK() && status != ErrorCodes::NoReplicationEnabled) {
             return status;
diff --git a/src/mongo/db/server_options.h b/src/mongo/db/server_options.h
index 5e4e934e2b0..7765a3579a0 100644
--- a/src/mongo/db/server_options.h
+++ b/src/mongo/db/server_options.h
@@ -236,11 +236,10 @@ struct ServerGlobalParams {
 
     } featureCompatibility;
 
-    // Feature validation differs depending on the role of a mongod in a replica set or
-    // master/slave configuration. Masters/primaries can accept user-initiated writes and
-    // validate based on the feature compatibility version. A secondary/slave (which is not also
-    // a master) always validates in the upgraded mode so that it can sync new features, even
-    // when in the downgraded feature compatibility mode.
+    // Feature validation differs depending on the role of a mongod in a replica set. Replica set
+    // primaries can accept user-initiated writes and validate based on the feature compatibility
+    // version. A secondary always validates in the upgraded mode so that it can sync new features,
+    // even when in the downgraded feature compatibility mode.
     AtomicWord<bool> validateFeaturesAsMaster{true};
 
     std::vector<std::string> disabledSecureAllocatorDomains;
diff --git a/src/mongo/db/server_options_helpers.cpp b/src/mongo/db/server_options_helpers.cpp
index c3b525ba8a1..c521a8921ab 100644
--- a/src/mongo/db/server_options_helpers.cpp
+++ b/src/mongo/db/server_options_helpers.cpp
@@ -603,13 +603,11 @@ Status validateServerOptions(const moe::Environment& params) {
         if (parameters.find("internalValidateFeaturesAsMaster") != parameters.end()) {
             // Command line options that are disallowed when internalValidateFeaturesAsMaster is
             // specified.
-            for (const auto& disallowedOption : {"replication.replSet", "master", "slave"}) {
-                if (params.count(disallowedOption)) {
-                    return Status(ErrorCodes::BadValue,
-                                  str::stream()
-                                      << "Cannot specify both internalValidateFeaturesAsMaster and "
-                                      << disallowedOption);
-                }
+            if (params.count("replication.replSet")) {
+                return Status(ErrorCodes::BadValue,
+                              str::stream() <<  //
+                                  "Cannot specify both internalValidateFeaturesAsMaster and "
+                                  "replication.replSet");
             }
         }
     }
diff --git a/src/mongo/db/startup_warnings_mongod.cpp b/src/mongo/db/startup_warnings_mongod.cpp
index 602810a373b..2f0ad080ee0 100644
--- a/src/mongo/db/startup_warnings_mongod.cpp
+++ b/src/mongo/db/startup_warnings_mongod.cpp
@@ -396,18 +396,6 @@ void logMongodStartupWarnings(const StorageGlobalParams& storageParams,
         warned = true;
     }
 
-    // Check if in master-slave mode
-    auto replCoord = repl::ReplicationCoordinator::get(svcCtx);
-    if (replCoord->getReplicationMode() == repl::ReplicationCoordinator::modeMasterSlave) {
-        log() << startupWarningsLog;
-        log() << "** WARNING: This node was started in master-slave replication mode."
-              << startupWarningsLog;
-        log() << "**          Master-slave replication is deprecated and subject to be removed "
-              << startupWarningsLog;
-        log() << "**          in a future version." << startupWarningsLog;
-        warned = true;
-    }
-
     if (warned) {
         log() << startupWarningsLog;
     }
diff --git a/src/mongo/db/storage/wiredtiger/SConscript b/src/mongo/db/storage/wiredtiger/SConscript
index 7378649b128..a957b7103f1 100644
--- a/src/mongo/db/storage/wiredtiger/SConscript
+++ b/src/mongo/db/storage/wiredtiger/SConscript
@@ -75,8 +75,6 @@ if wiredtiger:
             'storage_wiredtiger_customization_hooks',
             ],
         LIBDEPS_PRIVATE= [
-            # SERVER-31802 : remove this.
-            '$BUILD_DIR/mongo/db/repl/repl_coordinator_interface',
             '$BUILD_DIR/mongo/util/options_parser/options_parser',
             ],
         )
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
index 0d25901d6fc..9ad010a0957 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_kv_engine.h
@@ -241,7 +241,7 @@ public:
     /**
      * Initializes a background job to remove excess documents in the oplog collections.
      * This applies to the capped collections in the local.oplog.* namespaces (specifically
-     * local.oplog.rs for replica sets and local.oplog.$main for master/slave replication).
+     * local.oplog.rs for replica sets).
      * Returns true if a background job is running for the namespace.
      */
     static bool initRsOplogBackgroundThread(StringData ns);
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.cpp
index a7d086677d2..cd541d262f0 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.cpp
@@ -73,21 +73,13 @@ void WiredTigerOplogManager::start(OperationContext* opCtx,
         setOplogReadTimestamp(Timestamp(kMinimumTimestamp));
     }
 
-    auto replCoord = repl::ReplicationCoordinator::get(getGlobalServiceContext());
-    bool isMasterSlave = false;
-    if (replCoord) {
-        isMasterSlave =
-            replCoord->getReplicationMode() == repl::ReplicationCoordinator::modeMasterSlave;
-    }
-
     // Need to obtain the mutex before starting the thread, as otherwise it may race ahead
     // see _shuttingDown as true and quit prematurely.
     stdx::lock_guard<stdx::mutex> lk(_oplogVisibilityStateMutex);
     _oplogJournalThread = stdx::thread(&WiredTigerOplogManager::_oplogJournalThreadLoop,
                                        this,
                                        WiredTigerRecoveryUnit::get(opCtx)->getSessionCache(),
-                                       oplogRecordStore,
-                                       isMasterSlave);
+                                       oplogRecordStore);
 
     _isRunning = true;
     _shuttingDown = false;
@@ -162,9 +154,8 @@ void WiredTigerOplogManager::triggerJournalFlush() {
     }
 }
 
-void WiredTigerOplogManager::_oplogJournalThreadLoop(WiredTigerSessionCache* sessionCache,
-                                                     WiredTigerRecordStore* oplogRecordStore,
-                                                     bool isMasterSlave) noexcept {
+void WiredTigerOplogManager::_oplogJournalThreadLoop(
+    WiredTigerSessionCache* sessionCache, WiredTigerRecordStore* oplogRecordStore) noexcept {
     Client::initThread("WTOplogJournalThread");
 
     // This thread updates the oplog read timestamp, the timestamp used to read from the oplog with
@@ -237,12 +228,6 @@ void WiredTigerOplogManager::_oplogJournalThreadLoop(WiredTigerSessionCache* ses
 
         // Wake up any await_data cursors and tell them more data might be visible now.
         oplogRecordStore->notifyCappedWaitersIfNeeded();
-
-        // For master/slave masters, set oldest timestamp here so that we clean up old timestamp
-        // data.  SERVER-31802
-        if (isMasterSlave) {
-            sessionCache->getKVEngine()->setStableTimestamp(Timestamp(newTimestamp));
-        }
     }
 }
 
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.h b/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.h
index ac744f0d502..ac3bdc03c2c 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.h
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_oplog_manager.h
@@ -30,7 +30,6 @@
 #pragma once
 
 #include "mongo/base/disallow_copying.h"
-#include "mongo/db/repl/replication_coordinator.h"
 #include "mongo/db/storage/wiredtiger/wiredtiger_record_store.h"
 #include "mongo/stdx/condition_variable.h"
 #include "mongo/stdx/mutex.h"
@@ -81,8 +80,7 @@ public:
 
 private:
     void _oplogJournalThreadLoop(WiredTigerSessionCache* sessionCache,
-                                 WiredTigerRecordStore* oplogRecordStore,
-                                 bool isMasterSlave) noexcept;
+                                 WiredTigerRecordStore* oplogRecordStore) noexcept;
 
     void _setOplogReadTimestamp(WithLock, uint64_t newTimestamp);
 
diff --git a/src/mongo/dbtests/querytests.cpp b/src/mongo/dbtests/querytests.cpp
index 05fed16d3de..644b4a7bb2a 100644
--- a/src/mongo/dbtests/querytests.cpp
+++ b/src/mongo/dbtests/querytests.cpp
@@ -635,65 +635,6 @@ public:
     }
 };
 
-class OplogReplaySlaveReadTill : public ClientBase {
-public:
-    ~OplogReplaySlaveReadTill() {
-        _client.dropCollection("unittests.querytests.OplogReplaySlaveReadTill");
-    }
-    void run() {
-        const char* ns = "unittests.querytests.OplogReplaySlaveReadTill";
-
-        // Create a capped collection of size 10.
-        _client.dropCollection(ns);
-        _client.createCollection(ns, 10, true);
-
-        // The destructor for DBClientCursor runs killCursors. This must not be done while holding
-        // locks.
-        unique_ptr<DBClientCursor> c;
-
-        {
-            Lock::DBLock lk(&_opCtx, "unittests", MODE_X);
-            OldClientContext ctx(&_opCtx, ns);
-
-            BSONObj info;
-            _client.runCommand("unittests",
-                               BSON("create"
-                                    << "querytests.OplogReplaySlaveReadTill"
-                                    << "capped"
-                                    << true
-                                    << "size"
-                                    << 8192),
-                               info);
-
-            Date_t one = Date_t::fromMillisSinceEpoch(
-                LogicalClock::get(&_opCtx)->reserveTicks(1).asTimestamp().asLL());
-            Date_t two = Date_t::fromMillisSinceEpoch(
-                LogicalClock::get(&_opCtx)->reserveTicks(1).asTimestamp().asLL());
-            Date_t three = Date_t::fromMillisSinceEpoch(
-                LogicalClock::get(&_opCtx)->reserveTicks(1).asTimestamp().asLL());
-            insert(ns, BSON("ts" << Timestamp(one)));
-            insert(ns, BSON("ts" << Timestamp(two)));
-            insert(ns, BSON("ts" << Timestamp(three)));
-            c = _client.query(ns,
-                              QUERY("ts" << GTE << Timestamp(two)).hint(BSON("$natural" << 1)),
-                              0,
-                              0,
-                              0,
-                              QueryOption_OplogReplay | QueryOption_CursorTailable |
-                                  DBClientCursor::QueryOptionLocal_forceOpQuery);
-            ASSERT(c->more());
-            ASSERT_EQUALS(Timestamp(two), c->next()["ts"].timestamp());
-            long long cursorId = c->getCursorId();
-
-            auto pinnedCursor = unittest::assertGet(ctx.db()
-                                                        ->getCollection(&_opCtx, ns)
-                                                        ->getCursorManager()
-                                                        ->pinCursor(&_opCtx, cursorId));
-            ASSERT_EQUALS(three.toULL(), pinnedCursor.getCursor()->getSlaveReadTill().asULL());
-        }
-    }
-};
-
 class OplogReplayExplain : public ClientBase {
 public:
     ~OplogReplayExplain() {
@@ -1737,7 +1678,6 @@ public:
         add<TailCappedOnly>();
         add<TailableQueryOnId>();
         add<OplogReplayMode>();
-        add<OplogReplaySlaveReadTill>();
         add<OplogReplayExplain>();
         add<ArrayId>();
         add<UnderscoreNs>();
diff --git a/src/mongo/shell/db.js b/src/mongo/shell/db.js
index 4493b2a1192..300e446de95 100644
--- a/src/mongo/shell/db.js
+++ b/src/mongo/shell/db.js
@@ -1046,11 +1046,6 @@ var DB;
            use local
            db.getReplicationInfo();
       </pre>
-      It is assumed that this database is a replication master -- the information returned is
-      about the operation log stored at local.oplog.$main on the replication master.  (It also
-      works on a machine in a replica pair: for replica pairs, both machines are "masters" from
-      an internal database perspective.
-      <p>
       * @return Object timeSpan: time span of the oplog from start to end  if slave is more out
       *                          of date than that, it can't recover without a complete resync
     */
@@ -1062,10 +1057,8 @@ var DB;
         var localCollections = localdb.getCollectionNames();
         if (localCollections.indexOf('oplog.rs') >= 0) {
             oplog = 'oplog.rs';
-        } else if (localCollections.indexOf('oplog.$main') >= 0) {
-            oplog = 'oplog.$main';
         } else {
-            result.errmsg = "neither master/slave nor replica set replication detected";
+            result.errmsg = "replication not detected";
             return result;
         }
 
@@ -1209,12 +1202,6 @@ var DB;
             for (i in status.members) {
                 r(status.members[i]);
             }
-        } else if (L.sources.count() != 0) {
-            startOptimeDate = new Date();
-            L.sources.find().forEach(g);
-        } else {
-            print("local.sources is empty; is this db a --slave?");
-            return;
         }
     };