ServiceGuard signature in LVM physical volumes

[Jdamian]

Hi.

I know MC/ServiceGuard signs LVM physical volumes of managed volume groups (vgchange -c y). But is this signature the same in every MC/SG cluster (like a flag) or is a generated code (i.e, different values in different clusters) ?

I found some doc (I searched it again but I didn't found) that discussed this value is a 4-byte value starting at 0x12090 position in physical volume. I have three different MC/SG clusters but all they have the same value (0x100).

Thanx in advance

P.D: This value is 0x00 where physical volume is not managed by a cluster.

[Hoefnix]

The signiture is not the same on each cluster. If we move disks (using XP1024) between clusters, mc/serviceguard recognise that the disk(volumegroup) belongs to another cluster.

We overwrite this with the vgchange -c y on the new cluster.

HTH,
Peter

[Rajeev Shukla]

Yes, the value is different for different cluster, thats the reason why when you move a volume group from one cluster to another cluster you have to activate the VG in cluster mode again on another cluster. (to be cluster aware)

[Jdamian]

Then perhaps I'm wrong -- 0x12090 shouldn't be the location of that ID because three different clusters would use three different values.

Does anybody know that location ?

But I'm confused because the value contained in that location in non-cluster physical volumes (for instance, belonging vg00) is 0x0000 as expected.

[Dietmar Konermann · Accepted solution]

The cluster ID on LVM disks is a word at offset 8832. Dont't rely on this... it may change at anytime without notice.

Example:
echo "0d8332?U" | adb /dev/dsk/c4t0d0
208C: 1047653933

This translates to the cluster creation time:
# echo "0d8332?Y" | adb /dev/dsk/c4t0d0
208C: 2003 Mar 14 15:58:53

Best regards...
Dietmar.

[Francois LAURENT]

Hello,
Effectively the ClusterID is not the same. If you have a array replication (like srdf) between 2 arrays, and each array belong to 2 diffirent cluster, you'll have 2 differents ClusterID, and the disk can only be used by 1 cluster.

You can see the CLusterId with :
/usr/contrib/bin/lvm11 -a -d /dev/rdsk/cXtYdZ

--> "Cluster that can use this vg : 1003525071" for exemple.

francois