We have a Firebird server installation that periodically blocks all operations for a few minutes and then comes back alive on its own. This has happened about once a month for the last few months. During this blocking period, Firebird CPU usage is unusually low as this is a busy server. This server normally has 200-300 client attachments. The blocking time has varied from 2 minutes to over 10 minutes. During this time, no Firebird operations can be performed i.e. New connections are blocked along with existing connections. Upon recovery, Firebird continues processing without any other issues.
We have noticed that this has generally occurred, but not always, during a DB sweep. Our sweep interval is set to 0 and we are performing the sweep once a day as a scheduled task.