[OpenAFS] Re: Questions about 'vos move' and replicated volumes

Andrew Deason adeason@sinenomine.net
Mon, 10 Oct 2011 15:15:25 -0500

On Mon, 10 Oct 2011 15:55:55 -0400
Garance A Drosihn <drosih@rpi.edu> wrote:

> Also, if we have four different file servers, is there any downside to
> having some AFS volumes (such as '/home') replicated to all four
> fileservers?  Some kind of law of diminishing returns, for instance?
> Something like "One replica is nice, two is better because it gives
> you redundancy, three is even better for load-balancing purposes, but
> after that there isn't much point to adding more replicas?"

Generally speaking, no; more replication sites tends to be better. There
are sites where the max of 12/13 sites is often hit, and that maximum is
a sort of bottleneck.

During the actual release process, more sites will generally slow down
the release, of course. But this is usually not as much of a concern,
since releases tend to be very infrequent compared to accesses. The
volume should always appear available to clients during the release
regardless, anyway, and the speed shouldn't change much for smallish
volumes that just have dirs, mountpoints, etc.

So, it depends on what kind of volumes you're replicating of course, but
for volumes like /home, or root.cell, etc, usually I think you'd
replicate them as much as you can.

Andrew Deason