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Domain Administration

Dump Device Configuration

For large memory system configurations, it is no longer practical to configure the primary dump device to a partition on the boot disk. Starting with Solaris 8 OS, it is possible to assign an alternate dump device that can be configured to accept the large vmcore sizes that are expected with the Sun Fire 15K server. Given the fact that the kernel cage can be considered to use 1/16 of the total physical memory at start, and given that the kernel grows and shrinks according to the demands placed upon it by the applications that are running, the amount of space required to save a core file can be considerable. Best practice dictates that you should monitor a running system under varying conditions and pick a value for the dump device that is large enough to handle the kernel at its largest. In general, use a minimum of a 4 gigabytes for the dump device.

TIP

Use a dedicated dump device, and size it according to observed kernel growth at peak usage times.

Make sure there is enough disk space available on the dump device. In case a domain crash happens and root cause investigation is necessary, troubleshooting might be difficult without a kernel crash dump.

Swap Configuration

In most instances, the primary application dictates the amount of required swap space. For example, one third-party application stipulates that you should configure swap space on the order of four times the memory + 512 Megabytes. This would add up to an outrageous amount of swap space for a 578-gigabyte Sun Fire 15K server domain. For a large memory system, consult with the application vendors; otherwise, the current practice is to configure the swap space to be equal to the maximum amount of configured memory on one CPU/Memory board or 16 gigabytes (for 512-megabyte DIMMs), whichever is smaller. If dynamic configuration is used in the domain, the swap space should be configured to be equal to twice the maximum amount of configured memory on one CPU/Memory board or 32 gigabytes, whichever is smaller. These values should change to 32 gigabytes and 64 gigabytes respectively, using 1-gigabyte DIMMs.

TIP

Check application requirements for swap space. Use twice the maximum amount of memory on a single CPU/Memory board.

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