topic Re: reduce volume in Operating System - HP-UX

reduce volume

Nobody's Hero — Thu, 02 Oct 2003 10:15:56 GMT

I need to reduce the following oracle mount point:

/dev/vg09/lvol1 59523072 21802080 37426344 37% /u08

what command would I use, vgreduce ot lvreduce?

Re: reduce volume

Vitek Pepas — Thu, 02 Oct 2003 10:18:08 GMT

Unmount the filesystem and use lvreduce.

Re: reduce volume

John Poff — Thu, 02 Oct 2003 10:24:26 GMT

Hi,

You'll be looking for 'lvreduce'. The 'vgreduce' command is for removing physical volumes from your volume group.

I've never successfully done an lvreduce and had the filesystem survive it. I read here on the forum once that it can work but the poster suggested using 'fsadm' to defrag the filesystem first. I would most certainly get a good backup copy of the data before trying it.

The only way I've been able to do it before is to backup the data, remove the logical volume, recreate the logical volume at the smaller size, recreate the filesystem, and restore the data.

JP

Re: reduce volume

Pete Randall — Thu, 02 Oct 2003 10:28:23 GMT

Robert,

As JP mentioned, I've not had much success with lvreduce. If you have the space, I would make another logical volume of the desired size and copy the contents of /u08 into it, then blow /u08 away.

Pete

Re: reduce volume

Sundar_7 — Thu, 02 Oct 2003 10:28:31 GMT

Hi,

As said, only in very rare cases lvreduce succeed.

Two things

1) Defragment the filesyetm

fsadm -dDeE /mountpoint

2) Backup it up to the tapes or to an alternate location.

3) use fsadm to reduce the size and lvreduce.

if lvreduce is not successful then recreate the LV, newfs and restore from backup.

Thanks,

Sundar.

Re: reduce volume

Bryan D. Quinn — Thu, 02 Oct 2003 10:28:42 GMT

Hey Robert,

Unmount and use lvreduce. If the lvreduce frees up enough extents to free up an entire physical volume in the volume group, then you can do a vgreduce. The vgreduce will remove the designated physical volume from the volume group.

I would definately heed John's words though. I have performed a couple of lvreduce commands, but never in a production environment. I would most definately have a good backup. That safety net is a must.

-Bryan

Re: reduce volume

Helen French — Thu, 02 Oct 2003 10:29:25 GMT

The command should be 'lvreduce'. But remember these things when you do it:

1) Backup your data on this file system
2) If you have OnlineJFS, you can do it 'on the fly'
3) I would recommend doing 'backup first, lvremove second, lvcreate third and restore last' option. This will be more safe.

Re: reduce volume

GK_5 — Thu, 02 Oct 2003 11:28:49 GMT

The safest way to do is
1. Create new volume of desired size - Copy data to new volume - Remove original volume
Or
2. Backup the data - Remove original volume - Create new volume with desired size - Restore data.

-GK-