Soft-updates & du & df
glenn at antimatter.net
Wed Jul 13 23:45:55 GMT 2005
At 02:01 PM 7/13/2005, Hilco Wijbenga wrote:
>I've taken over the administration of a FreeBSD box and now I've run
>into a problem that I could not solve by means of Google or the FreeBSD
>mailinglist archives. I am quite familiar with (Gentoo) GNU/Linux but a
>complete newbie when it comes to FreeBSD.
>While I was doing some work I got an error about a device being full. As
>it turned out /var was completely full. Not a big problem because there
>were a few very big log files that I could throw away. Problem solved?
>Apparently not because
>root at svn[var]# df -h /var
>Filesystem Size Used Avail Capacity Mounted on
>/dev/ad2s1d 248M 246M -18M 108% /var
>root at svn[var]# du -hs /var
> 43M /var
The discrepancy between du and df usually happens when a log file is
deleted out from under syslogd. (or something similar) When that is done,
syslogd still has the file opened and will still be writing to that file at
the same offset it was before the file was deleted. To fix it, just stop
and restart syslogd and you should see all of the free space you are
expecting. (It could be something else, but when that happens in /var it's
>Shouldn't du and df roughly agree on the amount that's used/available?
>/var is mounted using soft-updates
>root at svn[var]# mount
>/dev/ad2s1a on / (ufs, local)
>devfs on /dev (devfs, local, multilabel)
>/dev/ad2s1e on /tmp (ufs, local, soft-updates)
>/dev/ad2s1f on /usr (ufs, local, soft-updates)
>/dev/ad2s1d on /var (ufs, local, soft-updates)
>/dev/gvinum/raid on /raid (ufs, local, soft-updates)
>According to what I found using Google regarding soft-updates this means
>that my changes are not written to disk immediately? Does that have
>anything to do with this?
>It looks like I didn't really solve the problem because if I try to copy
>a fairly big file (say 2MB) to the /var/log directory I get another 'No
>space left on device' even though there should now be about 200MB
>available. I can create small files though.
>How do I get du and df to agree again? Or do I have a different problem?
>Please let me know if I left out any important information.
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