July 27, 2012

DB2 Connect high CPU utilization

DB2 Connect servers are usually a good target for consolidation. Recently we observed relatively high CPU utilization even though only a small workload was being used. The oprofile and strace output showed that the system was busy doing semget() calls that failed. So a resource was missing. In the end it turned out to be a known problem in DB2 which is fixed starting DB2 9.7 FP5 and can also be circumvented in older versions by issuing a "db2trc alloc" during startup.
This is a typical consolidation problem - on individual dedicated servers this usually is not even noticed - however after consolidation this will be visible. An additional positive effect of fixing the problem is an improved throughput at higher transaction rates.

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