Anyone seen this before?

Our TSM server has crashed 3 nights running with a full log. We started
with Logmode=Rollforward and 3960 MB log. We tried increasing to 6012 MB,
which delayed the crash by about 45 mins.

We have DB backup trigger at 60%. But even when the backup ran, we got msg
"ANR4556W Attention: the database backup operation did not free sufficient
recovery log space to lower utilization below the database backup trigger.
The recovery log size may need to be increased." I guess this indicates a
transaction which is out of control - but I can't identify which TXN it is.

We have now switched to Logmode=normal, but I'm not sure it'll help.

Setup: TSM server 4.2.1.11 running on AIX 4.3.3 plus ML9 and patches.
Clients on NetWare, Windows, Unix (various flavours), plus TDP for R/3.

Any comments, suggestions, etc received gratefully.

Richard Foster