In a Storage Area Network (SAN) storage is visible to servers through multiple redundant paths, so that if one of the paths fails for some reason, the server still has access to the same storage through other paths. Except, if you happen to be using Ubuntu Server. Ubuntu server is apparently designed to hang if any of the storage paths fails. And it will also fail to notice if the path comes back up, so it will stay hung even after the situation is over. CS Department is using Ubuntu Server in the new csfs file server. Sorry about that, it probably was a mistake.

In case you are interested, you can read more from https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/690387.