Setup iSCSI storage on CentOS using yum

Posted on by under Linux, Storage, Systems Administration 

This was verified on CentOS 6.5, CentOS 5.9 and XenServer 6.2

This is a very basic guide on getting iSCSI storage up and running on a CentOS 6 server. You should obviously review more about security, authentication and other best practices when implementing this in a production environment.

Configuring iSCSI storage on CentOS linux:

1) Install iSCSI target via yum.

# yum install scsi-target-utils

Review the changes and agree to the install once you are ready to proceed.

2) Create the first target by editing the configuration file.

# vi /etc/tgt/targets.conf
<target iqn.2007-10.com.rowdydesign:disk0>
  backing-store /dev/md2
  initiator-address 192.168.0.1
  lun 1
</target>
  • target: This is iSCSI Qualified Name (IQN) of the target. Format is as follows:
    • literal iqn (iSCSI Qualified Name)
    • date (yyyy-mm) that the naming authority took ownership of the domain
    • reversed domain name of the authority (e.g. org.alpinelinux, com.example, to.yp.cr)
    • Optional “:” prefixing a storage target name specified by the naming authority.
  • backing-store: Path to your storage device.
  • initiator-address: IP Address you wish the service to listen on.
  • lun: Logical Unit Number, use this to force a specific LUN. Often times this is not needed and you should never use LUN 0.

3) Configure the iSCSI target daemon.

# /etc/init.d/tgtd start
# chkconfig --levels 235 tgtd on

This will start the target daemon and configure it to start at boot time on run levels 2, 3, and 5.

4) Configure your firewall (iptables).

# vi /etc/sysconfig/iptables

Allow traffic on all interfaces for port 3260 (iscsi target). This is very insecure, you should implement proper access control for all open ports based on your needs.

-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 3260 -j ACCEPT
# service iptables restart

Restart iptables to processes the newly added rule.

5) Do a basic check to ensure your configuration is correct.

# tgtadm --mode target --op show

You should see output similar to the following:

Target 1: iqn.2007-10.com.rowdydesign:disk0
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 5
            Initiator: iqn.2014-01.com.example:558f6e88
            Connection: 0
                IP Address: 192.168.0.1
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00010000
            SCSI SN: beaf10
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: null
            Backing store path: None
            Backing store flags: 
        LUN: 1
            Type: disk
            SCSI ID: IET     00010001
            SCSI SN: beaf11
            Size: 1869171 MB, Block size: 512
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: rdwr
            Backing store path: /dev/md2
            Backing store flags: 
    Account information:
    ACL information:
        192.168.0.0/24

If all of that looks correct, congratulations!

Written by Bret Mette

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