[Gluster-users] GlusterFS on a two-node setup

Ramon Diaz-Uriarte rdiaz02 at gmail.com
Mon May 21 13:00:57 UTC 2012

On Mon, 21 May 2012 09:35:05 +0100,Brian Candler <B.Candler at pobox.com> wrote:
> On Sun, May 20, 2012 at 06:09:47PM -0400, David Coulson wrote:
> > >I might have to look at DRBD more carefully, but I do not think it
> > >fits my needs: I need both nodes to be working (and thus doing
> > >I/O) at the same time. These are basically number crunching nodes
> > >and data needs to be accessible from both nodes (e.g., some jobs
> > >will use MPI over the CPUs/cores of both nodes ---assuming both
> > >nodes are up, of course ;-).
> > DRBD will let you do read/write on both nodes, but it requires a
> > clustered filesystem such as GFS2 or OCFS2 on top of it.

> Or more simply, with DRBD you can just split your space into two and mirror
> half in each direction.

> Server A: 300GB volume replicated to server B
> Server B: 300GB volume replicated to server A

> If one server dies, both volumes can be mounted on the same server.

> But if you need to access the *same* data on both nodes simultaneously, then
> you'd end up having to share it using something like NFS, in which case you
> may as well use glusterfs in the first place.

OK, understood. Yes, I need access to the very same data on both nodes
simultaneously. And glusterfs looks a lot simpler.



> > You are
> > also limited to a max of two nodes.

> Well, DRBD has to be configured in pairs (e.g. you can have one volume A->B,
> another B->C, another C->A).  This is what Ganeti gives you: each VM has its
> own DRBD on top of two LVM volumes on two nodes of your choice.

> Ganeti is primarily of benefit when doing a cluster of VMs.

> You can also do VMs with an image files stored on a gluster replicated
> volume.  I've not tested this, but I'm told that gluster 3.2 will lock the
> whole file while healing, whereas gluster 3.3 will perform much better.

> Regards,

> Brian.
Ramon Diaz-Uriarte
Department of Biochemistry, Lab B-25
Facultad de Medicina 
Universidad Autónoma de Madrid 
Arzobispo Morcillo, 4
28029 Madrid

Phone: +34-91-497-2412

Email: rdiaz02 at gmail.com
       ramon.diaz at iib.uam.es


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