How to Renumber datavg hdisk#s After a mksysb Restore

When rootvg is restored from a mksysb image, the hard disk names (numbers) may not coincide with those that existed prior to the restore. This condition occurs because mksysb always renumbers the disks according to the order that it "walks through" the bus.

This document provides a procedure to remap the hdisk numbers to the way they were prior to the mksysb. The document applies to AIX Version 4.

WARNING: This procedure, if not used carefully, can cause ODM corruption. Use it only if you are fully knowledgeable about the ODM.

1. Log in as root.

2. Before the mksysb backup and restore, to get a mapping of hdisk numbers, pvid, and vgs, execute lspv. Sample output is as follows:

   disk_name      pvid(disk label)    vg_names
   hdisk0         00004466c66c3498    rootvg
   hdisk1         00004466c7094f58    datavg01
   hdisk2         00000654fb425f0e    datavg01
   hdisk3         0001383388903964    datavg02
   hdisk4         00000654ab1bc125    datavg02
   hdisk5         00000654ab1de39e    datavg02
   

   pvid is the Physical Volume Identifier, which is similar to a disk label in a PC environment.

3. Perform the mksysb backup and restore.

4. Issue lspv again. Then, to obtain parent, connwhere, and PdDvLn, execute the following:

    odmget -q name=hdiskX CuDv
   

   The type of the disk is the rightmost part of PdDvLn (disk/scsi/???type???).

5. If the datavgs are varied on and their filesystems are mounted, unmount the filesystems with the umount command. Then execute varyoffvg datavg_name and exportvg datavg_name to dissociate the relationship between the pvs (hdisks) and the datavgs.

6. Issue lspv again to confirm that datavg names have changed to "none". Sample output is as follows:

   hdisk0         00004466c66c3498    rootvg
   hdisk1         00000654fb425f0e    none
   hdisk2         00004466c7094f58    none
   hdisk3         00000654ab1bc125    none
   hdisk4         0001383388903964    none
   hdisk5         00000654ab1de39e    none
   

7. For every pvid that has a different hdisk number, execute the following:

    rmdev -dl hdiskX
   

8. To associate the original hdisk numbers with the disks based on their pvid, execute:

    mkdev -c disk -l hdiskX -t ???type??? -s scsi -p scsiX -w X,0
   

9. Reimport all the datavgs by executing commands of the following form:

    importvg -y datavg_name one_hdisk_in_the_group
   

10. Execute mount -a to mount all datavg filesystems. Please ignore error messages related to filesystems that are already mounted. Use df to verify the presence of the filesystems.