Remove LVM info

[SAM_24]

Hi,

When I reinstall the OS still system remembers the old disk groups. How to remove the old info? Just running pvremove is enough?

Thanks

[Scott Van Kalken]

It depends.

I'd be tempted to do the lot.

if mirrored reduce logical volumes

remove logical volumes
remove volume groups
remove disks (if required).

Then again, the idea of an ignite is to rebuild a system that has crashed or to clone identical systems.

Scott.

[Michael Tully]

The LVM information will remain on the disk headers of volume groups other than vg00.

You can just re-use the disks into new volume groups if you don't require the old information.

To re-use the new disks use 'pvcreate -f /dev/rdsk/cxtydz

[Mike Hassell]

Raj,

As Michael has already stataed, the LVM info will remain on the disks even after you remove it from LVM.

The easiest way is to just reuse the disk with a pvcreate -f /dev/rdsk/cXtXdX, although if you really want to ensure that all data has been fully removed from the disk you can use dd:

dd if=/dev/zero of=/dev/dsk/cXtYdZ count=

I don't think /dev/zero is installed by default, but the major number is the same as /dev/null and the minor is 3, but I would check on that before creating the device if it is not already present.

The bottom line is that I wouldn't go to all the trouble of wiping the disks clean with dd, unless I had a reason to, otherwise a simple pvcreate will suffice.

Hope that helps.

-Mike

[Sean McConkey_2]

If you do a pvcreate -f and the disk is already in lvmtab, you may get an error message;

pvcreate: The physical volume "/dev/dsk/c0t5d0" is already recorded in the "/etc
/lvmtab" file.

You will need to "vgexport" the associated volume group, as well as removing the logical volumes etc. as already suggested.

I also delete and re-create the /dev/vg?? special files for all non-root volume groups.

eg rm -r /dev/vg01

mkdir /dev/vg01
mknod /dev/vg01/group c 64 0x010000

However I question why you are doing this if you are using Ignite on the same box, it was created on? Normally only required on a DR box where device names are similar.

HTH

Sean

[PIYUSH D. PATEL]

Hi,

pvcreate -f /dev/rdsk/c1t2d0

vgexport does not remove any information from the disks, it removes the info about the vg from the OS.

Piyush

[Sean McConkey_2]

Piyush,

It is necessary to remove the the information using vgexport from /etc/lvmtab before you can destroy the data on the disk with pvcreate.

This applies as already suggested if the physical volume already matches that stored in /etc/lvmtab. If it doesn't then pvcreate will work.

Disaster recovery is my game and I have to do this regularly when testing client systems.

[Craig Rants]

One way to tell if you have an LVM record on a disk is:

echo "0x2000?4S" | adb /dev/dsk/cXtXdX

you should see something like

2000: LVMREC01adjfakdjfa;

If you you have a record on that disk.

HTH,
C

[Robert Sipe]

pvcreate -f

[Frank Slootweg]

Because you say "remembers the old disk groups" (note "groups"), I assume that it still shows the old *volume* groups (i.e. "vgdisplay vg??"). If so, then it is best to vgexport the unwanted groups.

The others have already given solutions for the other scenarios.

BTW, "pvremove" does not exist.