Hello, anthonyjang2012!

Tuesday, May 29, 2012, 9:22:48 PM, you wrote:

a> Environment : Firebird 2.5.1 Super-Classic x64 on Windows 2008 R2 Server with 32 GB of RAM

a> We have a Firebird server installation that periodically blocks
a> all operations for a few minutes and then comes back alive on its own. This has happened
a> about once a month for the last few months. During this blocking
a> period, Firebird CPU usage is unusually low as this is a busy server. This server
a> normally has 200-300 client attachments. The blocking time has
a> varied from 2 minutes to over 10 minutes. During this time, no Firebird operations can be
a> performed i.e. New connections are blocked along with existing
a> connections. Upon recovery, Firebird continues processing without any other issues.

Looks like storage hangs. Have you looked at
- windows system log
- Perfmon, at the physical disk counters (queue, disk read bytes/sec,
disk writes bytes/sec)
?

and, anything in firebird.log?
do you use any UDFs?

--
Dmitry Kuzmenko, www.ib-aid.com