[DRBD-user] The old question: drbd on lvm or vice versa?

[Ralf W.]

We are using: HA-cluster with two Hardware Raid10(3TB) --> DRBD/pacemaker --> lvm --> iscsi-target --> shared IP --> <-- iscsi-initiator<--boot --> KVM node --> LVM.
failover works.  Still not sure if I should add dopd fencing... anybody???
Ralf




----- Original Message ----
From: Bart Coninckx <bart.coninckx at telenet.be>
To: drbd-user at lists.linbit.com
Sent: Thu, May 27, 2010 3:05:54 PM
Subject: Re: [DRBD-user] The old question: drbd on lvm or vice versa?

On Thursday 27 May 2010 14:45:39 Oliver Hoffmann wrote:
> > On Wednesday 26 May 2010 19:36:33 Oliver Hoffmann wrote:
> > > Hi list!
> > >
> > > I searched the web but I only found lvm on drbd and many problems
> > > concerning kvm or xen. I need lvm and drbd to have a flexible
> > > file server (without xen or the like).
> > >
> > > If I put lvm on top of drbd I run into problems. Such as a complex
> > > failover situation and I am limited to the physical space of a HD or
> > > partitions.
> > > Thus I think drbd on lvm would be better. In the end I want a
> > > drbd- and pacemaker- based file server with nfs and cifs and iSCSI.
> > > Plus I want to add one or more HD easily whenever needed or provide
> > > more or less disk space for a client or a share.
> > >
> > > What do you think?
> > >
> > > Thanks for suggestions!
> > >
> > > Cheers,
> > >
> > > Oliver
> > > _______________________________________________
> > > drbd-user mailing list
> > > drbd-user at lists.linbit.com
> > > http://lists.linbit.com/mailman/listinfo/drbd-user
> >
> > Oliver,
> >
> > I put DRBD on top of LVM for one sole reason: being able to resize
> > DRBD resources if I would ever need to. Without LVM below it, it's
> > much riskier (see DRBD manual).
> > I also put LVM at the same time on top of DRBD (see "nested LVM" in
> > the DRBD manual) which works great, provided you
> > change /etc/lvm/lvm.conf About the complex failover situation: if you
> > have cluster software taking care of this, it should not be referred
> > to any more as being "complex". Setting that software up might be
> > however.
> >
> > Hope this helps,
> >
> >
> > Bart
> 
> Hi Bart,
> 
> yes exactly. And this way I can have a drbd-device with a reasonable
> size for each service (cifs, nfs, etc) to begin with.
> 
> Cheers,
> 
> Oliver
> 
> 
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user
> 

Oliver,

having LVM on top of DRBD to me is mostly useful for things like being able to 
create seperate LUNs on top of your DRBD resource for iSCSI, or having 
snapshot functionality if you have a something worth snapshotting on those 
servers. 


Bart
_______________________________________________
drbd-user mailing list
drbd-user at lists.linbit.com
http://lists.linbit.com/mailman/listinfo/drbd-user