Cyrus, clusters, GFS - HA yet again

[Janne Peltonen]

Hi, and thanks for clearing things up!

On Sat, Oct 28, 2006 at 10:19:53AM +0200, Simon Matter wrote:
[...]
> 2) You have to consider GFS volumes
> a local storage because it is usually on SAN which is also virtually local
> storage. It really has nothing to do with networked filesystems like NFS.

That's what GFS is. The SAN provides the shared block device(s) for all the
nodes, GFS provides filesystem-level sharing. With GFS, different nodes
using the shared block device will be aware of what blocks are in use etc.
- GFS guarantees that each node's idea of the filesystem is in sync with
the others. That applies for file locks and mmap'd files and other such
things, too.

> AFAIK the trick with a GFS clustered Cyrus system is that you have two or
> more independant Cyrus servers sharing the same metadata and message store
> on the block device level, and not caring about each other, which means
> they all serve tha same mailboxes/users.

That's what I'm trying to create.

> IIRC there are people running
> Cyrus servers that way on other systems like Tru64 or Veritas cluster.

And that's precisely what I'm trying to find out: since there are people
that have succeeded in running Cyrus in an enviroment that's essentially
the same as mine, I'd like to know how they have found their way around
the DB error and other obstacles mentioned on this list in earlier
posts.


Regards,

--Janne