On ZFS, the filesystem that carries our homedirs, you may find yourself unable to delete files with full disk quota:
bfguser@bwui:~> cp testfile1 testfile2 cp: cannot create regular file `testfile2': Disk quota exceeded
Unfortunately you can not remove a file using the 'rm' command. E.g.:
bfguser@bwui:~> rm testfile1 rm: cannot remove file `testfile1': Disk quota exceeded
The trick is to copy /dev/null to the file you want to delete:
bfguser@bwui:~> ls -lah testfile1 -rw-r--r-- 1 bfguser bfggroup 16M 2009-03-23 10:44 testfile1 bfguser@bwui:~> cp /dev/null testfile1 bfguser@bwui:~> ls -lah testfile1 -rw-r--r-- 1 bfguser bfggroup 0 2009-03-23 11:41 testfile1 bfguser@bwui:~> rm testfile1 bfguser@gwui:~> ls -lah testfile1 /bin/ls: testfile1: No such file or directory
ZFS is a copy-on-write filesystem, so a file deletion transiently takes slightly more space on disk before a file is actually deleted. It has to write the metadata involved with the file deletion before it removes the allocation for the file being deleted. This is how ZFS is able to always be consistent on disk, even in the event of a crash.