[OpenAFS] OpenAFS through-the-NAT performance.

[Jim Rees]

This should go in an FAQ somewhere.

You can set a probe interval with "fs checks -interval" but that's not quite
what you want because it only sets the interval for down servers.

There is a "fs discon" command that will put you in to "nat mode," where all
servers will be probed at 60 second interval.  See
afs_SetCheckServerNATmode() in afs/afs_daemons.c.  This is not enabled in fs
by default, and I'm not sure there is code in afs_pioctl to call it.  The
reason for this is that it's a very unfriendly thing to do to your file
server, and we don't think the file server should be punished for your lack
of connectivity.

Of course if your afs admins are also deploying nats with short timeouts,
they get what they deserve.

Also be sure you have recent file servers.  Some important fixes went in
recently to track clients with poor (or mobile) connectivity.