For login servers, desktop computers etc. to be rebooted after updates, long running computations should always be done disconnected from the ssh connection to the compute server. This is possible using terminal multiplexors like tmux or GNU Screen. Here is an example for the use of tmux:
From the first ssh session, you should become independent of the kerberos/AFS credentials, which will be destroyed upon closing the ssh session:
kpagsh
You needs to obtain new credentials (Explanation):
kinit -l 2w --renewable -r 3month
Now you have got 2 weeks access to files on AFS and are entitled to renew these credentials for 3 months without reentering your password. With these credentials, you can start a tmux session, in which you will run your computations:
tmux
You can detach from the tmux session, which will continue to run in the background:
<Ctrl>+<B> <D>
After that, you can close the kpagsh and the ssh connection:
exit
exit
After logging back in via ssh, you can reconnect to your running tmux session:
tmux attach
If you have to renew your credentials while a computation is running, you can create a new window in tmux:
<Ctrl>+<B> <C>
From here, you can renew your kerberos/AFS credentials (in this example for 2 weeks):
kinit -R -l 2w
Now you can return to the original window 0 (and possibly later back to the new one with 1 instead of 0):
<Ctrl>+<B> <0>
Alternatively, you can close the window:
exit
Before you close the tmux session, you should destroy the kerberos/AFS credentials, which kpagsh made independent of the login:
kdestroy
You close the tmux session by closing the last window:
exit
(jan henrik, 2012-02-24)