topic Re: AIX, LUNs from XP disk array are not accessible in Disk Enclosures

AIX, LUNs from XP disk array are not accessible

Sergey Blatov — Fri, 14 Jul 2006 06:03:10 GMT

Hi, All,

Two LUNs on XP were used by a server with AIX 5.2. Then AIX 5.3 was cold-installed to this server. Volume group export was not done before upgrade. Now new AIX can not open these disks, VG import is not successful. Even dd from these disks is not working.
Tried to present these LUNs to HPUX, they are seen as zero size disks.
It seems that AIX locked the disks somehow and this lock is not cleared. If so, is there any way to clear such lock?
Thank you in advance.

Re: AIX, LUNs from XP disk array are not accessible

Ivan Ferreira — Fri, 14 Jul 2006 10:18:56 GMT

Sometimes, problems like this happens when the FC reservation was not released by the host. The problem is that I don't know how to clear FC reservations in AIX. Maybe you can find a support document for that. It would worth a try.

Re: AIX, LUNs from XP disk array are not accessible

Nigel Poulton — Sat, 15 Jul 2006 18:03:57 GMT

As the previous post has said this is probably some form of reserve on the LUNs.

If its a SCSI-2 reserve this can be released with any of the following methods -

1 - Your HP engineer can reset the CHIP ports that the LUN is presented on from the Engineers console on the SVP.

2 - You can issue a SCSI BUS reset to the CHIP port that the LUNs are presented on. To do this you can zone a server in to the CHIP ports that the LUN is rpesented on and then use the tool of your choice to issue SCSI BUS RESETS. If you have windows hosts you can use a tool called scsicmd.exe

Its best to do these during a maintenance window as both methods will release all SCSI-2 reserves on ALL LUNs on the the CHIP ports that are reset. Resetting the CHIP ports is a quick procedure but it can be a little disruptive. Ive had to do this many times in Microsoft Cluster environments and never had any problems although I always do it during a maintenance window.

If the reserve is a SCSI-3 persistent reserve on the LUNS these are not released by issuing a SCSI BUS RESET. HDS has a tool called DLMPR that you can run and it will show you if a LUN has a persistent reserve, what the reservation key is and also allows you to remove a persistant reserve. It might be worth asking your HP contacts if HP has a similar tool (after all the XP range is rebadged HITACHI storage).

HTH

mackem

Re: AIX, LUNs from XP disk array are not accessible

sathish kannan — Sat, 15 Jul 2006 19:23:51 GMT

Hello Sergey,

AIX keeps disks reservation when you "varyon" the volumegroup and will remove it when you "varyoff" volume groups. If the reservations are not porperly cleared you will get reservation errors on the host with "scsi_disk_2" and "scsi_disk_4", I believe.

If you can't access the disk using "dd", I hope the reservations is left on the LUNS and your HP CE or customer support has to remove by logging in to the array.

What is the status of the "hdisks" for the luns? Are they in "available" or "defined" state Have you tried cleaning the ODM and run "cfgmgr"?

Regards
Sathish