Apple Xsan 1.1 - Manual (Page 102)

102 Chapter 7 Solving SAN Problems
A Client is Unable to Use a Volume After a Fibre Channel
Interruption
If a client loses its Fibre Channel connection to the SAN (because a cable is unplugged,
for example), the client might not recognize LUNs in an Xsan volume after the
connection is restored. If this happens, restart the client to remount the volume.
If problems persist, restart all SAN devices: Begin with Xserve RAID systems, continue
with SAN controllers, and finally restart all clients.
To check if a computer is seeing Xsan volume LUNs:
m Open Disk Utility on the computer and look for the LUNs in the list of disks and
volumes.
From the Command Line
You can also check for accessible LUNs using the
cvlabel -l
or
diskutil list
command in Terminal.
SAN Performance Declines Periodically and Predictably
If client computers experience simultaneous problems with SAN performance
(dropped video frames, for example), some system activity might be using needed
resources. In particular, if all clients experience dropped frames at around 4:30
A . M . local
time on Saturdays, the problem is probably due to the weekly system maintenance
scripts. One script in particular, which rebuilds the locate database, can have a
noticeable impact on file system performance.
To disable the scripts:
m Disable the script that runs “locate.updatedb” in /etc/weekly, or disable all the weekly
maintenance scripts by commenting out the “periodic weekly” command in
/etc/crontab.