path: root/README

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                Linux* Open-iSCSI

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                                                February 28, 2005

Contents
========

- 1. In This Release
- 2. Introduction
- 3. Installation
- 4. Open-iSCSI daemon
- 5. Open-iSCSI Configuration Utility
- 6. Configuration
- 7. Getting Started
- 8. TBD
- Appendix A. SendTargets snapshot.



1. In This Release
==================

This file describes the Linux* Open-iSCSI Initiator. The software was
tested on AMD Opteron (TM) and Intel Xeon (TM). 

The latest development release is available at:
http://www.open-iscsi.org

For questions, comments, contributions send e-mail to:
open-iscsi@googlegroups.com 

    1.1. Features
    
    - highly optimized and very small-footprint data path;
    - multiple outstanding R2Ts;
    - persistent configuration database;
    - SendTargets discovery;
    - CHAP;
    - PDU header Digest;
    - multiple sessions;
    - multi-connection sessions.
    
    For the most recent list of features please refer to:
    http://www.open-iscsi.org/cgi-bin/wiki.pl/Roadmap

    

2. Introduction
===============

Open-iSCSI project is a high-performance, transport independent,
multi-platform implementation of RFC3720 iSCSI.

Open-iSCSI is partitioned into user and kernel parts.

The kernel portion of Open-iSCSI is a from-scratch code
licensed under GPL. The kernel part implements iSCSI data path
(that is, iSCSI Read and iSCSI Write), and consists of two
loadable modules: iscsi_if.ko and iscsi_tcp.ko.

User space contains the entire control plane: configuration
manager, iSCSI Discovery, Login and Logout processing,
connection-level error processing, Nop-In and Nop-Out handling,
and (in the future:) Text processing, iSNS, SLP, Radius, etc.

The user space Open-iSCSI consists of a daemon process called
iscsid, and a management utility iscsiadm.


3. Installation
===============

As of today, the Open-iSCSI Initiator requires a host running the
Linux operating system with kernel version 2.6.11, or later. You need to
enable "Cryptographic API" under "Cryptographic options" in the
kernel config. You also need to enable "CRC32c CRC algorithm" if
you use header or data digests. They are the kernel options,
CONFIG_CRYPTO and CONFIG_CRYPTO_CRC32C, respectively.

Compilation of the kernel Open-iSCSI modules requires a path
to kernel sources:

	make KSRC=<kernel-src>

or cross-compilation:

	make KSRC=<kernel-src> KARCH="ARCH=um"

If you choose to install the Debian packages instead of building from source,
please read the file /usr/share/doc/linux-iscsi/README.debian for information
on how to build kernel modules against your specific kernel.

4. Open-iSCSI daemon
====================

The daemon implements control path of iSCSI protocol, plus some management
facilities. For example, the daemon could be configured to automatically 
re-start discovery at startup, based on the contents of persistent 
iSCSI database (see next section).

For help, run:

	./iscsid --help

Usage: iscsid [OPTION]

  -c, --config=[path]     Execute in the config file (/etc/iscsid.conf).
  -f, --foreground        run iscsid in the foreground
  -d, --debug debuglevel  print debugging information
  -u, --uid=uid           run as uid, default is current user
  -g, --gid=gid           run as gid, default is current user group
  -h, --help              display this help and exit
  -v, --version           display version and exit



5. Open-iSCSI Configuration Utility
===================================

Open-iSCSI persistent configuration is implemented as a DBM database
available on all Linux installations.

The database contains two tables:

- Discovery table (discovery.db);
- Node table (node.db).

The regular place for iSCSI database files: /var/db/iscsi/*.db

The iscsiadm utility is a command-line tool to manage (update, delete,
insert, query) the persistent database.

The utility presents set of operations that a user can perform 
on iSCSI nodes, sessions, connections, and discovery records.

Note that some of the iSCSI Node and iSCSI Discovery operations 
do not require iSCSI daemon (iscsid) loaded.

For help, run:

	./iscsiadm --help

Usage: iscsiadm [OPTION]

  -m, --mode <op>         specify operational mode op = <discovery|node>
  -m discovery --type=[type] --portal=[ip:port] --login
                          perform [type] discovery for target portal with
                          ip-address [ip] and port [port]. Initiate Login for
                          each discovered target if --login is specified
  -m discovery            display all discovery records from internal
                          persistent discovery database
  -m discovery --record=[id] --login
                          perform discovery based on record [id] in database
  -m discovery --record=[id] --op=[op] [--name=[name] --value=[value]]
                          perform specific DB operation [op] for specific
                          discovery record with [id]. It could be one of:
                          [new], [delete], [update] or [show]. In case of
                          [update], you have to provide [name] and [value]
                          you wish to update
  -m node                 display all discovered nodes from internal
                          persistent discovery database
  -m node --record=[id] [--login|--logout]
  -m node --record=[id] --op=[op] [--name=[name] --value=[value]]
                          perform specific DB operation [op] for specific
                          node with record [id]. It could be one of:
                          [new], [delete], [update] or [show]. In case of
                          [update], you have to provide [name] and [value]
                          you wish to update
  -m session              display all active sessions and connections
  -m session --record=[id[:cid]] [--logout]
                          perform operation for specific session with
                          record [id] or display statistics if no operation
                          specified. Operation will affect one connection
                          only if [:cid] is specified
  -d, --debug debuglevel  print debugging information
  -V, --version           display version and exit
  -h, --help              display this help and exit


    Usage Examples:

    1) SendTargets iSCSI Discovery:

	    ./iscsiadm -m discovery --type sendtargets --portal 192.168.1.1:3260

    2) iSCSI Login:

	    ./iscsiadm -m node --record 0f23e4 --login

    3) iSCSI Logout:

	    ./iscsiadm -m node --record 0f23e4 --logout

    4) Changing iSCSI parameter:

	    ./iscsiadm -m node --record 0f23e4 --op update \
		    -n node.cnx[0].iscsi.MaxRecvDataSegmentLength -v 65536

    5) Adding custom iSCSI Node:

	    ./iscsiadm -m node --op new --portal 192.168.0.1:3260
	    new iSCSI node record added: [0a45f8]

    6) Removing iSCSI Node:

	    ./iscsiadm -m node --op delete --record 0a45f8

    7) Display iSCSI Node configuration:

	    ./iscsiadm -m node --record 0a45f8

	or

	    ./iscsiadm -m node --op show --record 0a45f8


6. Configuration
================

The default configuration file is /etc/iscsid.conf. This file contains
only configuration that could be overwritten by iSCSI Discovery,
or manualy updated via iscsiadm utility. Its OK if this file does not
exist in which case compiled-in default configuration will take place
for newer discovered Target nodes.

See the man page and the example file for the current syntax.
(no man page yet...)


7. Getting Started
==================

Right now there is no installation script. Just load the module with
command:

	insmod iscsi_if.ko
	insmod iscsi_tcp.ko

after that start iSCSI daemon process:

	./iscsid

or alternatively, start it with debug enabled and with output
redirected to the current console:

	./iscsid -d8 -f &

and use configuration utility to add/remove/update Discovery records,
iSCSI Node records or monitor active iSCSI sessions:

	./iscsiadm


To login:

	    ./iscsiadm -m node --record <node rec> --login

where <node rec> is the record of a discovered or manually
added iSCSI Target Node (for iscsiadm usage examples see
previous sections).


8. TBD
======

To be completed:

    - Kernel tracing and Troubleshooting
    - Immediate and not-so-immediate plans
    - Useful scripts
    - White paper on Open-iSCSI design


Appendix A. SendTargets iSCSI Discovery session snapshot.
=========================================================

-bash-2.05b# ./iscsiadm -m discovery -tst -p 10.16.16.223:3260
[02f611] 10.16.16.223:3260,1 iqn.2002-07.com.ttechnologies.target.a
[01acd1] 17.1.1.223:3260,1 iqn.2002-07.com.ttechnologies.target.a
-bash-2.05b#
-bash-2.05b# ./iscsiadm -m node
[02f611] 10.16.16.223:3260,1 iqn.2002-07.com.ttechnologies.target.a
[01acd1] 17.1.1.223:3260,1 iqn.2002-07.com.ttechnologies.target.a
-bash-2.05b#
-bash-2.05b# ./iscsiadm -m discovery -tst -p 10.16.16.227:3260
[02fb91] 10.16.16.227:3260,1 iqn.2001-04.com.example:storage.disk2.sys1.xyz
-bash-2.05b#
-bash-2.05b# ./iscsiadm -m node
[02f611] 10.16.16.223:3260,1 iqn.2002-07.com.ttechnologies.target.a
[02fb91] 10.16.16.227:3260,1 iqn.2001-04.com.example:storage.disk2.sys1.xyz
[01acd1] 17.1.1.223:3260,1 iqn.2002-07.com.ttechnologies.target.a