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

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


I have a few questions about replicated volumes.

In the utility script named 'mvto.pl', the script says:

     # If the volume is replicated and the read/write is already
     # on the right server, we won't actually move it.  Just make
     # sure there's also a replica on the same partition if the
     # volume is replicated.  Otherwise, move the read/write
     # site and its corresponding replica if applicable.

Is there some significant problem which might come up if someone
wanted to move a RW volume plus the RO version from one partition
on a file-server to a different partition on the same fileserver?
Or is the script just assuming there isn't much to gain by moving
the AFS volume in that situation?

We put some new disks on our file servers, and I'm moving volumes
from the old disks (vicepa) to the new disks (vicepb).  Once I'm
done with that, I'll unmount the old disks, and then mount another
set of new disks as the vicepa's on all the file servers.

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?"

Garance Alistair Drosehn                =     drosih@rpi.edu
Senior Systems Programmer               or   gad@FreeBSD.org
Rensselaer Polytechnic Institute;             Troy, NY;  USA