AIX

have machine running AIX 4.3.3ML 11. It's rootvg has about 1GB of space available and is made up of 2 9GB drives. We are going to upgrade it to AIX 5.x but wanted more disk space for the upgrade. So was going to install 2 new 18GB drives. The plan was to bring the 2 18GB drives in as hdisk# and hdisk#, extend rootvg, make some mirrors (mklvcopy), change the bootlist, remove some mirrors and eventually the machine would be booting from the 18GB drives and we'd have tons of space for the upgrade.

What I didn't notice is that the rootvg on the 4.3.3ML11 box had a PP size of 16. So when I installed the 2 18GB drives, I got the following "nasty-gram" when attempting to extend the vg.

root@hostX:/# extendvg rootvg hdisk18
0516-1162 extendvg: Warning, The Physical Partition Size of 16 requires the creation of 1084 partitions for hdisk18. The limitation for volume group rootvg is 1016 physical partitions per physical volume. Use chvg command with -t option to attempt to change the maximum Physical Partitions per Physical volume for this volume group.

0516-792 extendvg: Unable to extend volume group.

As the error message states I think I can use the CHVG command (chvg -t 2 rootvg) to change the root VG's characteristics, which would hopefully allow me to add the 2 18GB drives.

I can't recall the last time I used the CHVG command to change a VG's charateristics like this. Is there risk here? I used the chvg -t command on test system but can't quite duplicate the scenario I'd be facing on the 4.3.3ML11 box.

Thoughts? Basically I'm concerned with the risk in using the CHVG -T command.

Thanks all!

Ok, take this with a giant spoonful of salt since I've never used the chvg command and I'm fairly new to AIX. However, I remember reading in a training manual that the issue is the larger you set the limit for PPs, the fewer disks you can add to a volume group. But here you just want 4 disks in the group anyway so it shouldn't matter.

One other hint for you, my contracting project where I started doing a lot of AIX a few months back was to upgrade old servers. The more senior AIX guys here recommended I go from 4.3.3 to 5.1 first, then from 5.1 to 5.3 after. Not sure if you'll want to do that, but it is something you can consider.

One other method you could do, is if you can afford an outage, is to do a MKSYSB backup and then restore it onto the 18GB disks, this will take care of the PP sizes in the volume group or you could use alt_disk_install, but I can't remember is that was in 4.3.3

Regards
Craig Murray