Strange diskspace loss

[Антон Клесс]

Hello.

I'm running 7.2-RELEASE amd64. Uptime 24 days.
I was told that server stoped to send emails and started to look at. There
are strange things:

# df -h
Filesystem        Size    Used   Avail Capacity  Mounted on
/dev/aacdu0s1a    7.7G    582M    6.6G     8%    /
devfs             1.0K    1.0K      0B   100%    /dev
/dev/aacdu0s1d     31G    276M     28G     1%    /tmp
/dev/aacdu0s1f    350G    125G    197G    39%    /usr
/dev/aacdu0s1e     31G     29G    -25M   100%    /var
/dev/aacdu1s1d    450G    3.0G    411G     1%    /var/db/mysql
fdescfs           1.0K    1.0K      0B   100%    /dev/fd

/var is out of space. Hmm.

# du -sh /var
3,3G    /var

How can it be so? o_O