AIX LUNs(LUNz) presented to host?

LUNz is the logical unit number that an application client uses to communicate with, configure and determine information about an SCSI storage array and the logical units attached to it. The LUN_Z value shall be zero.

LUNz has been implemented on CLARiiON arrays to make arrays visible to the host OS and PowerPath when no LUNs are bound on that array.  When using a direct connect configuration, and there is no Navisphere Management station to talk directly to the array over IP, the LUNZ can be used as a pathway for Navisphere CLI to send Bind commands to the array.

LUNz also makes arrays visible to the host OS and PowerPath when the host’s initiators have not yet ‘logged in to the Storage Group created for the host.  Without LUNz, there would be no device on the host for Navisphere Agent to push the initiator record through to the array. This is mandatory for the host to log in to the Storage Group. Once this initiator push is done, the host will be displayed as an available host to add to the Storage Group in Navisphere Manager (Navisphere Express).

LUNz should disappear once a LUN zero is bound, or when Storage Group access has been attained.

To conclude, the LUNz devices will be shown up in following two scenarios:
1. when arraycommpath is set to 1(enabled) and host HBAs are registered and login to Clariion array, but no “Storage Group” is configured for this host.
2. when there is no LUN configured using HLU0(Host LUN0) in the host “Storage Group”.

Figure-1 Storage Group with no LUN assigned using HLU0
To resolve this LUNz issue:
1. Verify LUNz hdisk number by issue:

## lsdev -Cc disk | grep LUNZ

 

hdisk5 Available 08-08-08     EMC CLARiiON FCP LUNZ Disk

hdisk6 Available 08-08-08     EMC CLARiiON FCP LUNZ Disk

hdisk7 Available 08-08-08     EMC CLARiiON FCP LUNZ Disk

hdisk8 Available 08-08-08     EMC CLARiiON FCP LUNZ Disk

 

2. set one of the LUNs assigned to the host using HLU0.

Figure-2 Assign LUN with HLU0
3. Remove each LUNZ device with command:
#rmdev -dl hdisk5
#rmdev -dl hdisk6
#rmdev -dl hdisk7
#rmdev -dl hdisk8

4. Reconfigure devices with command cfgmgr or emc_cfgmgr

Leave a Reply

Your email address will not be published. Required fields are marked *

CAPTCHA * Time limit is exhausted. Please reload the CAPTCHA.

This site uses Akismet to reduce spam. Learn how your comment data is processed.