This is a question regarding OpenAFS (any AFS will do, but I'm
guessing OpenAFS is the most common.)

Is it possible to have either / and / or:

Servers with replicas hosting a read/write volume.  One of the servers
goes down, but the clients use the server that is still up...

Or one of the servers goes down, and the clients keep working on the
local cached copy.

I'm considering switching from NFS, but its a big step, and I'm trying
to suss out what the advantages are...

Thanks!