High availability email server...

[Fabio Corazza]

Pascal Gienger wrote:
> There are techniques to handle these situations - for xfs (as an
> example) consider having *MUCH* RAM in your machine and always mount it
> with logbufs=8.

Is XFS so RAM intensive?

> I would NEVER suggest to mount the cyrus mail spool via NFS, locking is
> important and for these crucial things I like to have a real block
> device with a real filesystem, so SANs are ok to me.

Sorry, please bear with my ignorance, I'm not very informed about NFS,
but what's wrong with locking against a real block device?

> We are having here a RAID device with 1,5 TB wich is shared between 2
> mail nodes and 2 test nodes. The switch can be done manually (10 seconds
> downtime) and - if you wish - via Heartbeat HA software. The only
> dangerous thing is to ensure that NEVER, really NEVER a second node
> mounts your SAN partition while another has mounted it already.
> Immediately kernel halts and data losses are the result.

There are file systems like GFS that have been written for that, even if
they are pretty CPU and I/O intensive (I use it for multimedia sharing -
a lot a lot of images that needs to be shared across 4 nodes having
Apache to serve them).



Fabio