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

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### Semaphores

If the number of semaphores is too low, HADB can fail and display this error message:

    No space left on device

This can occur either while starting the database, or during run time. Since the semaphores are provided as a global resource by the operating system, the configuration depends on all processes running on the host, and not the HADB alone. In Solaris, configure the semaphore settings by editing the `/etc/system` file.

To run the nodes, NNODES (the number of nodes submitted implicitly by `--hosts` option to the HADB) and NCONNS connections (HADB configuration parameter `NumberOfSessions`, default value being 100) per host, use the following semaphore settings:

    set semsys:seminfo_semmap = <default=10> + NNODES
    set semsys:seminfo_semmni = <default=10> + NNODES
    set semsys:seminfo_semmns = <default=60> + (NNODES * 8)
    set semsys:seminfo_semmnu = <default=30> + NNODES + NCONNS

If you plan to run multiple nodes per host, make sure `semmap = NNODES`. Use the `sysinfo` and `sysdef` commands to inspect the settings.

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