I have had three occurrences (on one of my own servers) since our
upgrade from FB 2.0 to FB 2.1.1 where suddenly the server (superserver
on windows, using local/xnet connections) stops accepting new database
attachments or service attachments.

isc_attach_database() fails and reports -904 (unsuccessful execution
caused by an unavailable resource) with specific engine code 335544375
and message 'unavailable database' (of course).

At the time of this starts happening the log shows :


TIP (Server) Sun Aug 17 21:21:38 2008
XNET error: get_free_slot() failed

TIP (Server) Sun Aug 17 21:21:38 2008
Database:
unknown ISC error 0


To cure it, a simple stop of the superserver service, followed by a
start is enough. So the server process is still responsive. It looks
like people with existing connections are not impaired until of course
they try to open new attachments.

I have a workaround which consists in restarting the firebird service
at 02:00 in the morning, as it looks like I need it running 2 to 3 or
more days before it happens.

With 2.0 (I think that was 2.01 we never moved to 2.03 I think) this
never happened.

To be complete, here is the exhaustive content of our firebird.conf
file on these kind of configurations:

LegacyHash = 0
Authentication = native
ConnectionTimeout = 10
RemoteServiceName = tip_fb
RemoteServicePort = 31600
TcpRemoteBufferSize = 16384
IpcName = Global\TIP-FIREBIRD
CreateInternalWindow = 0

Except for 'LegacyHash = 0' and 'Authentication = native' which were
added for FB 2.1.1, we have used that configuration with FB 2.0 since
FB 2.0 was released without any similar issue. In case you might ask,
this is configured in such a way so that we can run a superserver
instance in isolation from any other version or instance of Firebird
on the machine.

--
Olivier Mascia
T.I.P. Group S.A.
http://www.tipgroup.com

-----
TIP (Server) Fri Aug 29 15:49:24 2008
XNET error: get_free_slot() failed

TIP (Server) Fri Aug 29 15:49:24 2008
Database:
unknown ISC error 0
...
TIP (Server) Wed Sep 03 11:42:54 2008
XNET error: get_free_slot() failed

TIP (Server) Wed Sep 03 11:42:54 2008
Database:
unknown ISC error 0