Help iSCSI initiator commands for linux.

May 27, 2010 at 1:53 pm (linux, TechTips, Uncategorized) (iscsi)

I’ve been doing a lot of work lately with Red Hat Enterprise Virtualization.  The hosts that I am using are currently connecting to the SAN using iSCSI.  However, in the future they will be connecting with Fiber Channel instead.

I find myself having to remember how to use the iSCSI initiator a lot.  Here are some quick notes on how to do the most common tasks.

Discover available targets from a discovery portal

iscsiadm -m discovery -t sendtargets -p ipaddress

Log into a specific target
iscsiadm -m node -T targetname -p ipaddress -l

Log out of a specific target
iscsiadm -m node -T targetname -p ipaddress -u
Display information about a target
iscsiadm -m node -T targetname -p ipaddress
Display statistics about a target
iscsiadm -m node -s -T targetname -p ipaddress
Remove the portal address to receive information or statistics about all targets.
Display list of all current sessions logged in
iscsiadm -m session
View iSCSI database regarding discovery
iscsiadm -m discovery -o show
View iSCSI database regarding targets to log into
iscsiadm -m node -o show
View iSCSI database regarding sessions logged into
iscsiadm -m session -o show
View if the targets are multipathed (MPIO)
multipath -ll
If it is multipathed, you will see output like below (this is an example of two LUNs, both multipathed).  Note that this show the MPIO mode is round-robin:
36000d77100000b117de986015d5d5746 dm-7 FALCON,IPSTOR DISK
[size=20G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
 \_ 12:0:0:0 sdb 8:16  [active][ready]
 \_ 13:0:0:0 sdd 8:48  [active][ready]
36000d771000002767de9860330139e10 dm-8 FALCON,IPSTOR DISK
[size=200G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=0][active]
 \_ 12:0:0:1 sdc 8:32  [active][ready]
 \_ 13:0:0:1 sde 8:64  [active][ready]

Here is a very helpful article that covers similar commands, etc.
http://kbase.redhat.com/faq/docs/DOC-6388