bdf and du conflicting

[Larry Scheetz]

I am running out of space on a particular volume. I have deleted files but still looks like space is being taken up? When I do a du on the directories it does not add up near to what BDF is saying. BDF is saying I am almost out of space and du is not? Anything I can do to clear this up or find out why the system thinks I am using this space? Thank you very much for your time.

[S.K. Chan · Accepted solution]

The bdf and du tool is totally different. du shows the number of currently allocated blocks and counts the blocks you've just deleted as free but bdf shows the free disk space available. The difference is if a still active process allocated blocks eg for a logfile that you've just deleted, bdf counts these as still occupied. This won't change until the process closes the file (deallocates the blocks) as it usually happens when the process terminates. You need to find that process/processes. If you can't find any, it means these have terminated pre-maturely leaving the space still locks up. A reboot would clear it up.

[Paul Thomson_2]

Have you tried perhaps seeing what processes are still using the volume group.
eg
fuser /dev/vg/lvolname

I have had instances where although the space had been cleared the logical volume has still been in use and does not update the change. You can also perhaps try
fuser -k which will kill the pids using the filesystem, or perhaps stop the pids individually. Once the pid in question is dead the filesystem should show the correct usage.
Harsh measures taken include even unmounting the filesystem, then re mounting
eg
umount/mount /dev/vg/lvol
Cheers
Paul

[Darrell Allen]

Hi Larry,

There could have been a file deleted that was still open by a process. bdf will report that space used but du can't find an inode for it to know that space is used.

This often happens when someone removes or renamesa a log file and then recreates it without stopping the log program. syslog.log is one of those.

Darrell