Apple released OS X Server 10.6.5 which addresses several key fixes.
One important fix is with Xsan, 10.6.5 “Improves reliability of fibre channel connections, resolving a potential Xsan volume availability problem.”
More information is available here:
OS X Server: http://support.apple.com/kb/HT4249
OS X Client: http://support.apple.com/kb/HT4250
We suggest updating to 10.6.5 to address Xsan stability.