[linux-lvm] LVM2, NFS and random device (major:minor) numbers

[Sander Steffann]

Hi Paul,

> NFS depends on what the server says the underlying device id is of the 
> exported volume and if that changes, then NFS mounts are going to change 
> out from under themselves.  And everytime I add a volume and reboot the 
> device ids change.

Unfortunate, but true. One of the side-effects of having dynamic volumes. 
Also note that you would get similar trouble if, for example, you added a 
SCSI device with a lower SCSI-id than an existing SCSI device. /dev/sdb1 
would become /dev/sdc1, etc.

> I finally come upon this old post to this list:
> http://www.redhat.com/archives/linux-lvm/2005-May/msg00029.html

The part that can solve everything for you is:
>> These days, that's configurable.
>> See 'man exports' fsid=num.

With an explicit fsid=n for every export, you tell the NFS server to ignore 
the device-id, and use the specified fsid instead. That way you get 
consistent NFS exports, without being dependent on the underlying 
device-ids.

I have had the same trouble as you have, and this solution works great.
Sander.