AIX

When attempting to extend rootvg to a new physical disk I received the following message:

Code:

0516-1162 extendvg: Warning, The Physical Partition Size of 64 requires the
        creation of 1093 partitions for hdisk5.  The limitation for volume group

        rootvg is 1016 physical partitions per physical volume.  Use chvg comman
d
        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.

Can I change the allowed maximum phsical partitions while the system is running or do I have to perform a mksysb and make a change? What would be the steps to perform this. Thank you.

Short answer: yes, you can, but you should not.

You can double and even quadruple the number of physical partitions per physical volume, but only at the expense of halving (quartering) the number of physical volumes in the volume group. Normally a VG can hold up to 32 PVs with 1016 PPs each. You can introduce a so-called "factor" (of 2 or 4), which multiplies the PPs per PV but divides the number of PVs in the VG at the same time. The maximum storage capacity of the VG remains constant therefore. (See the man page for "chvg" for details about this factor.)

If you are starting to add disks (PVs) to the VG which have more PVs than allowed this is an indicator that you have chosen a bad value for the PP size compared to the storage demands of the VG. Probably the VG has been created long ago and the demands have outgrown the VGs capacity.

This is why you better back up the VG, recreate it with a more sensible PP size and then restore from the backup. You have a great opportunity to reorganise your storage layout and still stay flexible in every direction. In my experience introducing these VG factors is usually a last-ditch effort to avoid such a reorganisation and in the long run that causes more problems than are solved by it. Do yourself a favour and reorganise your storage now, when you *can* instead of some day very near in the future when you *must* do it.

I hope this helps.

bakunin

Hi bakunin,
Yes your post does help. I will have to do some more research on how to back it up and recreate with a different PP size. I do have a file system on it that is large, but only 5 percent of it is being used. I would like to shrink it though Being that it is AIX5.2 and the volume group is rootvg I will proceed with caution. Perhaps talking to IBM support would be a good first step. Thank you.

hmmm except you have really loads of memory on your box, and therefor a large virtual memory area (what I don't really believe), a 36 GB disk should be more than sufficient for rootvg - except you have a lot of application data in the same vg.
If that is the case, I would suggest you rather create a new VG with bigger pp size on the new disk and a few new filesystems and than just copy/paste the data to these new filesystems. Since you're able to change afterwards even mountpoints, you can keep the filesystem structure you already have.
Keeping a system clean might be the better solution than what you're going to do.
You can than drop the no longer needed filesystems from rootvg and can use the space to extend filesystems, if required.
Kind regards
Nicki

Change the "factor" with -t option within chvg.

Find the informations of supporting PPs in AIX with any version.

read it first.