[OpenAFS] Setting affinity for fileservers on afs-clients

Garance A Drosehn drosih@rpi.edu
Sun, 25 Oct 2015 21:38:32 -0400

We have some AFS volumes which hold data for various web servers on
campus.  These volumes are replicated on multiple file servers,
because that's an intelligent thing to do with important data.

We also have multiple web servers, because it's also intelligent to
split the web-serving load across machines, and to have redundancy
in our web servers.

All of these are virtual machines on various VMware hypervisors.
While doing some benchmarks on new AFS file servers, I noticed that
AFS data is transferred much faster if the afs client machine is on
the same hypervisor as the afs file server that it's contacting.

Is there some way to encourage this to happen on our web servers?
If the important AFS data is replicated on both afsfs1 (on vmhyper1)
and afsfs2 (on vmhyper2), can we have a web-server on vmhyper1
prefer afsfs1 instead of afsfs2?  I'd want it to still use afsfs2
if it can't reach afsfs1 (for the case where vmhyper1 is fine, but
afsfs1 is being rebooted for some reason).

Nothing urgent here.  Just wondering.

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