Since you do not have any real disk partitions in a container, /etc/fstab (or most part of it) is no longer needed. Empty it (excluding the lines for <code>/dev/pts</code>, <code>/proc</code>, <code>/sys</code> and such):

egrep '/dev/pts|/dev/shm|/proc|/sys' /vz/private/123/etc/fstab.old > /vz/private/123/etc/fstab