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I inherited an IBM System Storage DS4000 SAN with an AIX environment running Oracle RAC (3 nodes). One of the nodes crashed, so I got the system up and running with 2 nodes; however, the node that crashed was the node that was managing the backups. The backups were stored on a LUN in the SAN.

Due to the lack of documentation, I can see how they're mapped from /etc/filesystems, but I'm not sure how the AIX environment mapped these LUNs at bootup (other than the mapping association from the SAN management interface). I want to re-map the LUNs used for backups from the old node to one of the remaining nodes, but I'm concerned about losing the data on the LUNs.

I found some instructions here, but that seems like it's only for new LUNs. If I re-map the LUN to a new host, would the existing data on that LUN stay intact?

Update 1:

It looks like I knew less than I thought.

I created a new array on my storage controller called test and a new LUN called logbackup to test my theory and mapped it to one of the nodes as LUN 12.

On that node, when I ran cfgmgr, I ran into an error and followed these instructions to resolve it.

With cfgmgr working, I thought I'd be able to see the LUN, but I don't--or at least, the output of lspv, lscfg and lsdev -Cc Disk don't give me the information I can easily translate.

I've unmapped it and remapped the LUN a few times, but there is no change to the list of hdisks when I run cfgmgr.

Update 2:

Looks like I was reading my lscfg output incorrectly. I changed the LUN from 12 to 255 and saw a change in the lscfg. It mapped the LUN to hdisk16 so I added it as a physical volume using chdev -l hdisk16 -a pv=yes. Then, running fget_config -Av, I was able to confirm the LUN mapped properly. Now, it's just a matter of mounting it, writing to it, then migrating it to my other node to see if the data stays intact.

  • What's your question? Do you need help figuring out how to get it to mount? Or are concerned that mounting the volume will mess something up? – longneck Dec 18 '13 at 21:25
  • I am concerned that re-mapping the LUN will require me to wipe the data before I can use it on a "new" system (same OS, different box). Are my concerns unfounded? And if I re-map it from the SAN management interface, what service in AIX picks it up? Or do I need to reboot for a process to pick it up? – CIA Dec 19 '13 at 15:54
  • can you tell us more about the actual SAN, MUCH more, is this FC/iSCSI/FCoE etc., adapter types - everything please – Chopper3 Dec 19 '13 at 17:40
  • FiberChannel SCSI – CIA Dec 20 '13 at 14:47

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