Soft-updates & du & df

Ivailo Tanusheff i.tanusheff at
Thu Jul 14 07:55:59 GMT 2005

Hilco Wijbenga <hilco.wijbenga at> 
Sent by: owner-freebsd-questions at
07/14/2005 12:01 AM

freebsd-questions at

Soft-updates & du & df


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

even though

root at svn[var]# du -hs /var
 43M    /var

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.



You can force the updates to be written to the disk using sync (8) for the 
whole system or fsync on a specific files. Or you can just wait a while so 
the updates are written to thr disk.

Ivailo Tanusheff

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