Difference between revisions of "ISCSI Target"

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(Setup with LIO Target: + Tips/Tricks: targetstatus to list current open sessions)
m (Upstream Documentation: fix targetcli link, moved yesterday)
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=== Upstream Documentation ===
=== Upstream Documentation ===
* [http://www.linux-iscsi.org/wiki/RTSadmin targetcli/rtsadmin]
* [http://www.linux-iscsi.org/wiki/Targetcli targetcli]
* [http://www.linux-iscsi.org/wiki/Lio-utils_HOWTO LIO utils]
* [http://www.linux-iscsi.org/wiki/Lio-utils_HOWTO LIO utils]
* You can also use {{ic|man targetcli}} when you installed the ''free branch'' version {{AUR|targetcli-fb}}.
* You can also use {{ic|man targetcli}} when you installed the ''free branch'' version {{AUR|targetcli-fb}}.

Revision as of 15:24, 1 March 2012

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Summary help replacing me
How to set up an iSCSI Target using different tools.
iSCSI Target
iSCSI Initiator
iSCSI Boot

With Wikipedia:iSCSI you can access storage over an IP-based network.

The exported storage entity is the target and the importing entity is the initiator.

There are different modules available to set up the target. The SCSI Target Framework (STGT) was the standard before linux 2.6.38. The current standard is the LIO target. The iSCSI Enterprise Target (IET) is an old implementation and SCSI Target Subsystem (SCST) is the successor of IET and was a possible candidate for kernel inclusion before the decision fell for LIO.

There are packages available for LIO, STGT and IET in the AUR (see below).

Setup with LIO Target

LIO target is included in the kernel since 2.6.38. However, the iSCSI target fabric is included since linux 3.1.

The important kernel modules are target_core_mod and iscsi_target_mod, which should be in the kernel and loaded automatically.

/etc/rc.d/target is included in targetcli-fbAUR when you use the free branch or a less clean version in lio-utilsAUR when you use the original targetcli or lio-utils directly.

You start LIO target with
# /etc/rc.d/target start

This will load necessary modules, mount the configfs and load previously saved iscsi target configuration.

# /etc/rc.d/target status
you can show some information about the running configuration.

You might want to include target in your rc.conf#Daemons.

You can use targetcli to create the whole configuration or you can alternatively use the lio utils tcm_* and lio_* directly (deprecated).

Using targetcli

It is recommended to install the free branch targetcli-fbAUR from AUR with the dependencies rtslib-fbAUR and configshell-fbAUR.

There is also the original targetcliAUR package available, but it is additionally dependent on lio-utils and epydoc. The external manual is only available in the free branch.

The config shell creates most names and numbers for you automatically, but you can also provide your own settings. At any point in the shell you can type help in order to see what commands you can issue here.

Tip: You can use tab-completion in this shell
After starting the target (see above) you enter the configuration shell with
# targetcli

In this shell you include a block device (here: /dev/disk/by-id/md-name-nas:iscsi) to use with

/> cd backstores/block
/backstores/block> create md_block0 /dev/disk/by-id/md-name-nas:iscsi
Note: You can use any block device, also raid and lvm devices. You can also use files when you go to fileio instead of block.
You then create an iSCSI Qualified Name (iqn) and a target portal group (tpg) with
...> cd /iscsi
/iscsi> create
Note: With appending an iqn of your choice to create you can keep targetcli from automatically creating an iqn

In order to tell LIO that your block device should get used as backstore for the target you issue

.../tpg1> cd luns
.../tpg1/luns> create /backstores/block/md_block0

Then you need to create a portal, making a daemon listen for incoming connections:

.../luns/lun0> cd ../../portals
.../portals> create

Targetcli will tell you the IP and port where LIO is listening for incoming connections (defaults to (all)). You will need at least the IP for the clients. The port should be the standard port 3260.

In order for a client/initiator to connect you need to include the iqn of the initiator in the target configuration:

...> cd ../../acls
.../acls> create iqn.2005-03.org.open-iscsi:SERIAL

Instead of iqn.2005-03.org.open-iscsi:SERIAL you use the iqn of an initiator. It can normally be found in /etc/iscsi/initiatorname.iscsi. You have to do this for every initiator that needs to connect. Targetcli will automatically map the created lun to the newly created acl.

Note: You can change the mapped luns and whether the access should be rw or ro. See help create at this point in the targetcli shell.

The last thing you have to do in targetcli when everything works is saving the configuration with:

...> cd /
/> saveconfig

The will the configuration in /etc/target/saveconfig.json. You can now safely start and stop /etc/rc.d/target without losing your configuration.

Tip: You can give a filename as a parameter to saveconfig and also clear a configuration with clearconfig


Authentication per CHAP is enabled per default for your targets. You can either setup passwords or disable this authentication.

Disable Authentication

Navigate targetcli to your target (i.e. /iscsi/iqn.../tpg1) and

.../tpg1> set attribute authentication=0
Warning: With this setting everybody that knows the iqn of one of your clients (initiators) can access the target. This is for testing or home purposes only.
Set Credentials

Navigate to a certain acl of your target (i.e. /iscsi/iqn.../tpg1/acls/iqn.../) and

...> get auth

will show you the current authentication credentials.

...> set auth userid=foo
...> set auth password=bar

Would enable authentication with foo:bar.

Using (plain) LIO utils

You have to install lio-utilsAUR from AUR and the dependencies (python2).

Tips & Tricks

  • With targetstatus you can list the current open sessions. This script is included in the targetcli-fbAUR package, but can also be used together with lio-utils or the original targetcli. It needs rtslib or rtslib-fb.

Upstream Documentation

Setup with SCSI Target Framework (STGT)

You will need the Package tgtAUR from AUR.

External Howto

This is also linked on the official STGT website.

Setup with iSCSI Enterprise Target (IET)

You will need iscsitarget-kernelAUR and iscsitarget-usrAUR from AUR.

Create the Target

Modify /etc/iet/ietd.conf accordingly

Hard Drive Target

Target iqn.2010-06.ServerName:desc
Lun 0 Path=/dev/sdX,Type=blockio

File based Target

Use "dd" to create a file of the required size, this example is 10GB.

dd if=/dev/zero of=/root/os.img bs=1G count=10
Target iqn.2010-06.ServerName:desc
Lun 0 Path=/root/os.img,Type=fileio

Start server services

rc.d start iscsi-target

Also you can "iscsi-target" to DAEMONS in /etc/rc.conf so that it starts up during boot.

See also