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| author | Nick Vatamaniuc <vatamane@gmail.com> | 2022-07-01 17:00:05 -0400 |
|---|---|---|
| committer | Nick Vatamaniuc <nickva@users.noreply.github.com> | 2022-07-05 15:28:54 -0400 |
| commit | e41465ec852be4f97685309b4644e796395ada74 (patch) | |
| tree | 122b6203aa2c87a217df3f38adb48279c1e88902 | |
| parent | eb2f8d998779246b3847d2ba4341837926ec9f4b (diff) | |
| download | couchdb-e41465ec852be4f97685309b4644e796395ada74.tar.gz | |
Add an option to let custodian always use [cluster] n value
In cases when the application prevents creating dbs with non-default n values
(n=1, n=2) setting `[custodian] use_cluster_n_as_expected_n = true` can help
detect cases when the shard map itself was manpulated and by mistake ended up
with less than `[cluster] n` copies for some ranges.
By default the behavior is unchanged and n value will be deduced from the
number of copies indicated in the shard map documents.
| -rw-r--r-- | rel/overlay/etc/default.ini | 10 | ||||
| -rw-r--r-- | src/custodian/src/custodian_util.erl | 9 |
2 files changed, 18 insertions, 1 deletions
diff --git a/rel/overlay/etc/default.ini b/rel/overlay/etc/default.ini index cefd9e493..71c0d59d9 100644 --- a/rel/overlay/etc/default.ini +++ b/rel/overlay/etc/default.ini @@ -753,3 +753,13 @@ port = {{prometheus_port}} ; to disable this setting could be if the views need an upgrade but located on ; read-only file system. ;commit_on_header_upgrade = true + +[custodian] +; When set to `true`, force using `[cluster] n` values as the expected n value +; of of shard copies. In cases where the application prevents creating +; non-default n databases, this could help detect case where the shard map was +; altered by hand, or via an external tools, such that it doesn't have the +; necessary number of copies for some ranges. By default, when the setting is +; `false`, the expected n value is based on the number of available copies in +; the shard map. +;use_cluster_n_as_expected_n = false diff --git a/src/custodian/src/custodian_util.erl b/src/custodian/src/custodian_util.erl index 866bcacb1..41f51507d 100644 --- a/src/custodian/src/custodian_util.erl +++ b/src/custodian/src/custodian_util.erl @@ -87,7 +87,11 @@ fold_dbs(Id, Shards, State) -> IsLive = fun(#shard{node = N}) -> lists:member(N, State#state.live) end, LiveShards = lists:filter(IsLive, Shards), SafeShards = lists:filter(IsSafe, Shards), - TargetN = mem3_util:calculate_max_n(Shards), + TargetN = + case cluster_n_is_expected_n() of + true -> cluster_n(); + false -> mem3_util:calculate_max_n(Shards) + end, Acc0 = State#state.acc, Acc1 = case mem3_util:calculate_max_n(LiveShards) of @@ -171,6 +175,9 @@ get_n_rings(N, Ranges, Rings) -> cluster_n() -> config:get_integer("cluster", "n", 3). +cluster_n_is_expected_n() -> + config:get_boolean("custodian", "use_cluster_n_as_expected_n", false). + maintenance_nodes(Nodes) -> {Modes, _} = rpc:multicall(Nodes, config, get, ["couchdb", "maintenance_mode"]), [N || {N, Mode} <- lists:zip(Nodes, Modes), Mode =:= "true"]. |