Before CernVM-FS 2.11, having the file descriptor limit set to a very large number
will result in a very slow cvmfs performance in certain situations.
This is due to certain operations looping over all possible file descriptors,
instead of just the used/opened ones.
This issue is resolved in CernVM-FS 2.11.
If the /tmp file system is on xfs, the publisher node cannot be used with AUFS.
On such systems, adding the mount option xino=/dev/shm/aufs.xino can be
a workaround. In general, new repositories should use OverlayFS if available.