[DRBD-user] Migrating NFS to a DRBD block device

Lars Ellenberg Lars.Ellenberg at linbit.com
Fri Oct 15 19:15:38 CEST 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


/ 2004-10-15 09:51:17 -0700
\ Jeff Buck:
> OK, I know this would be a bit of a kludge, but wouldn't it work to put
> LVM on top of the block device. Wouldn't the device number in that case
> stay the same, even if you popped drbd in or out of the loop?

well, but first you'd need to migrate from your current bdev to lvm.
same problem there.

and then, you can as well migrate directly to drbd.

but Bernd was right mentioning the fsid parameter
(you need a recent nfsd implementation, though...)

if you can figure out the correct fsid,
migration of the server should then be possible
even without rebooting / remounting the clients.

> > > so there is no chance (without patching the nfs server to support
> > > a configurable mapping of exported handle numbers to block dev
> > > numbers) to migrate the data on the nfs server to some other block
> > > device without rebooting / forcefully remounting the clients.
> > 
> > I have currently not much time to give a detailed explanation how to
> > solve this, Omar, could you try to search via google for my name and
> > 'fsid'?
> > I have answered this kind of question already at least two times in
> > English.  If you shouldn't find it, I will try to answer more in
> > detail in about 6-7 hours. 
> > The basic idea is to fake the fsid via the fsid mount option.  You
> > have to do this before you switch to drbd, so you set the fsid
> > export option, reexport, remount from your clients on the fly and
> > finally can switch the server to drbd.
> > 
> > 
> > Cheers,
> >  Bernd


	Lars Ellenberg

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