High availability ... again

Andrew Morgan morgan at orst.edu
Tue Jun 22 13:58:59 EDT 2004

On Tue, 22 Jun 2004, Etienne Goyer wrote:

> Tore Anderson word of wisdom where :
> >   There's a third option, which is the one I prefer the most:  shared
> >  block device.
> Well, I did not consider that option since the SAN become a single
> point-of-failure, and that is a big no-no according to the
> specifications I have at the moment.
> If it would have been possible, it would have been my first choice though.

Most SANs are not single points of failure, unless you consider the whole
SAN catching fire a single point of failure.  A properly designed SAN can
have complete hardware redundancy, so unless you commit some
administrator error...  :)

We have a SAN that we use for user home directories here built from Sun T3
Enterprise pairs.  It uses RAID 5 for disk redundancy, has two FC
controllers that can failover to each other, has redundant FC links to a
pair of FC switches, and the server has redundant FC links to the

We've had both disks and controllers fail without even a hiccup, and we've
even added more storage to the SAN *and* expanded the file system on the
fly.  Veritas Volume Manager and File System are wonderful.


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