[Mimedefang] McAfee uvscan workaround (was: uvscan exceedingly slow)

[Ole Holm Nielsen]

In the thread
http://lists.roaringpenguin.com/pipermail/mimedefang/2003-September/007892.html
I asked for help with excessive delays in MimeDefang because our
McAfee uvscan caused a 13-second delay on every message.

Examining further the output of "strace uvscan ...", it was obvious
that two 5-6 second delays occur when uvscan apparently tries to
open the /dev/hda device.  Since our server runs with SCSI disks,
it turned out that /dev/hda is a CD-ROM drive (with no CD in it).
The strace pointed to a problem by outputting at the time of delays:
open("/dev/hda", O_RDONLY)              = -1 ERRNO_123 (No medium found)

It dawned upon me that I should try to put a CD in the drive and mount it.
Voila !  The 13-second overhead in running uvscan is now down to 0.015 seconds !
This workaround will keep me happy as long as I remember to leave a
CD mounted in the CD drive :-)  Perhaps this problem will be generic
to all systems with SCSI-disks ?  I've opened a support case with McAfee
support asking for a (hopefully) better solution.

SUMMARY:  If you use McAfee uvscan, time it from the command-line.
If it seems slow, use "strace uvscan" to see if uvscan is having
delays in opening your CD-ROM device.  If so, mount a CD and retry.

BTW, if you run on Redhat 9 uvscan has problems with shared libraries
and won't run.  The solution is given here:
http://www.sng.ecs.soton.ac.uk/mailscanner/serve/cache/153.html

Ole Holm Nielsen
Department of Physics
Technical University of Denmark