Sun Java System Application Server Enterprise Edition 8.1 2005Q2 Performance Tuning Guide

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## Memory Allocation

It is essential to allocate sufficient memory for HADB, especially when it is co-located with other processes.

The HADB Node Supervisor Process (NSUP) tracks the time elapsed since the last time it performed monitoring. If the time exceeds a specified maximum (2500 ms, by default), NSUP restarts the node. The situation is likely when there are other processes in the system that compete for memory, causing swapping and multiple page faults. When the blocked node restarts, all active transactions on that node are aborted.

If Application Server throughput slows and requests abort or time out, make sure that swapping is not the cause. To monitor swapping activity on Unix systems, use this command:

    vmstat -S

In addition, look for this message in the HADB history files. It is written when the HADB node is restarted, where M is greater than N:

    Process blocked for .M. sec, max block time is .N. sec

The presence of aborted transactions will be signaled by the error message

    HADB00224: Transaction timed out or HADB00208: Transaction aborted.

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