Enabling iSCSI on Linux hosts

While autoconfiguration of iSCSI takes care of most connectivity between CDS and hosts, from time to time we need to do the procedure manually.

 

To enable iSCSI on a Linux host:

 

Make sure you have the iscsiadm package installed.

 

“# rpm –qa | grep iscsi” should show you something similar to “iscsi-initiator-utils-6.2.0.865-6.el5.x86_64.rpm”. If you see nothing, you need to get the package installed using "yum" or similar.

 

Install with

yum install iscsi-initiator-utils

 

Set iscsi services to start on boot.

 

# chkconfig iscsid on

# service iscsid start

# chkconfig iscsi on

# service iscsi start

 

Verify the services are running

 

service iscsid status

 

If it is not running, you might need to try start it up with

service iscsid force-start

 

Find the IQN of the Linux host

 

# cat /etc/iscsi/initiator.iscsiname

 

example:

 

[root@localhost ~]# cat /etc/iscsi/initiatorname.iscsi 

InitiatorName=iqn.1994-05.com.redhat:e18fec10c2c6

[root@localhost ~]# 

Discover the iscsi targets on the CDS.

 

# iscsiadm –m discovery –t st –p ip.address.of.CDS.iscsi.target

Example:

# iscsiadm -m discovery -t st -p 183.24.13.1

183.24.13.1:3260,1 iqn.1986-03.com.ibm:2145.clu5-b.clu5-b-node1

Log onto the iscsi target discovered above - Use the IQN of the target host returned from running the discovery command above.

 

# iscsiadm -m node -T iqn.from.command.above -p ip.address.of.iscsi.target -l

 

Example

iscsiadm -m node -T iqn.1986-03.com.ibm:2145.clu5-b.clu5-b-node1 -p 183.24.13.1 -l

Automatically logon at boot - Use the IQN of the target host returned from running the discovery command above.

 

# iscsiadm -m node -T iqn.from.command.above -p ip.address.of.iscsi.target  --op update –n node.startup –v automatic

 

Example

iscsiadm -m node -T iqn.1986-03.com.ibm:2145.clu5-b.clu5-b-node1 -p 183.24.13.1 --op update -n node.startup -v automatic

Scan the iscsi bus for LUNs

 

# iscsiadm -m node --rescan

 

The LUNs will now be available for mounting by Linux using standard Linux mount syntax.

  

Using the above process with Actifio protection.

 

1.    Enable iSCSI on the linux host (instructions above)

2.    Install the UDS connector on the linux host

3.    Add the linux host (Actifio UI)

4.    Discover the applications on the linux host (Actifio UI)

5.    Protect the discovered applications (Actifio UI)

On RHEL and CentOS release 6.3 (Final) iSCSI initator name is in this file:

[root@seanrhel1 ~]# cat /etc/iscsi/initiatorname.iscsi

Also on CentOS 5.8, by the way.

# iscsiadm -m session -P 3

This command is also helpful, this will tell the iSCSI devices mapped to the linux host from a specific iSCSI Target.