extendvg and rootvg Post: 302308356

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Operating Systems AIX extendvg and rootvg Post 302308356 by bakunin on Friday 17th of April 2009 08:01:19 PM

04-17-2009

Registered User

Quote:

Originally Posted by jyoung

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

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LEARN ABOUT V7

vgcfgrestore

VGCFGRESTORE(8) 					      System Manager's Manual						   VGCFGRESTORE(8)

NAME

       vgcfgrestore - restore volume group descriptor area

SYNOPSIS

       vgcfgrestore [-d|--debug] [-f|--file filename] [-l[l]|--list] [-h|--help] [-M|--Metadatatype1|2] [-t|--test] [-v|--verbose] VolumeGroupName

DESCRIPTION

       vgcfgrestore  allows  you  to  restore  the metadata of VolumeGroupName from a text backup file produced by vgcfgbackup.  You can specify a
       backup file with --file.  If no backup file is specified, the most recent one is used.  Use --list for a list of the available  backup  and
       archive files of VolumeGroupName.

OPTIONS

       -l | --list -- List files pertaining to VolumeGroupName
	      List  metadata  backup  and  archive  files  pertaining  to VolumeGroupName.  May be used with the -f option.  Does not restore Vol-
	      umeGroupName.

       -f | --file filename -- Name of LVM metadata backup file
	      Specifies a metadata backup or archive file to be used for restoring VolumeGroupName.  Often this file has been created with  vgcfg-
	      backup.

       See lvm for common options.

REPLACING PHYSICAL VOLUMES

       vgdisplay  --partial  --verbose will show you the UUIDs and sizes of any PVs that are no longer present.  If a PV in the VG is lost and you
       wish to substitute another of the same size, use pvcreate --restorefile filename --uuid uuid (plus additional arguments as appropriate)	to
       initialise  it with the same UUID as the missing PV.  Repeat for all other missing PVs in the VG.  Then use vgcfgrestore --file filename to
       restore the volume group's metadata.

SEE ALSO

       lvm(8), vgcreate(8)

Sistina Software UK					 LVM TOOLS 2.02.95(2) (2012-03-06)					   VGCFGRESTORE(8)