Hi,
We are working on db2 v9.1 on AIX.
This morning all the backups on our server failed because the instance was stopped unknowingly. Now I am trying to find the cause behind what forced the instance to stop.
Looked in db2diag.log and also instance.nfy. There i can only find:

2010-08-08-22.52.07.832767 Instance:db2inst1 Node:000
PID:3469484(db2agent (JCRDB6D4) 0) TID:1 Appid:*LOCAL.db2inst1.100808073503
buffer pool services sqlbIsSpaceOnPathForConts Probe:20 Database:xxx

ADM6101W While attempting to extend table space "SYSCATSPACE" (ID "0"), there
were less than "67108864" bytes free on
"path". This space is reserved for use by DB2 and/or the operating system.

2010-08-08-22.52.07.834055 Instance:db2inst1 Node:000
PID:3469484(db2agent (xxx) 0) TID:1 Appid:*LOCAL.db2inst1.100808073503
buffer pool services sqlbAllocateExtent Probe:825 Database:xxx

ADM6044E The DMS table space "SYSCATSPACE" (ID "0") is full. If this is an
autoresize or automatic storage DMS tablespace, the maximum table space size may have been reached or the existing containers or storage paths cannot grow any more. Additional space can be added to the table space by either adding new containers or extending existing ones using the ALTER TABLESPACE SQL statement. If this is an autoresize or automatic storage DMS table space, additional space can be added by adding containers to an autoresize table space or by adding new storage paths to an automatic storage database.

How do I assure that this only caused the instance to stop. I can find no other information apart from this specifically talking about the instance stop.

Any crash related messages in the db2diag.log?

no such message also.

It would be easier if you attach db2diag.log