[Gluster-users] Monitor replicated Gluster setup ?

[Brian Candler]

On Thu, Jul 12, 2012 at 07:38:18AM +0000, Stefan Schloesser wrote:
> > To switch IP for what? glusterfs in replicated mode, using the native 
> > (FUSE) client, doesn't need this.  The client talks to both backends, 
> > and if either backend fails, it continues to work.
> [>]
> I am slightly confused here, I don't have a client (at least in the sense
> of a different machine), it's only 2 servers with each running an apache
> which uses the Filesystem (simply mounted).

You mean Apache is reading the glusterfs bricks locally? That's wrong; any
writes would screw up replication.  You should mount the glusterfs volume
via a FUSE mount, and have Apache access files through that mountpoint. 
That's what I mean by a "client".  The fact it happens to be on the same
server as where one of the glusterfs storage bricks runs is irrelevant.

Even if Apache is only reading files, going through the glusterfs mountpoint
will ensure that when the two replicas are out of sync you see the correct
version of each file (which will happen after one node has been down for a
while, writes have happened to the other node, and then the first node has
come back up again, and background healing is taking place)

> The reason for the ip switch is the apache: if one fails the other should
> take other the workload and continue operation, this is done via the ip
> switch.

Then that's just switching the public IP which apache listens on, and is
nothing to do with glusterfs.  Both servers can have the glusterfs volume
mounted all the time.

Regards,

Brian.