Platform-Specific Memory Options

The total amount of usable memory is limited only by the virtual memory of the system.

Wired Memory Pool

On HP and Solaris platforms, you can designate a specified amount of memory as wired memory. Wired memory is shared memory that is locked into physical memory. The kernel cannot page this memory out of physical memory.

Wired memory may improve Sybase IQ performance when other applications are running on the same machine at the same time. Dedicating wired memory to Sybase IQ, however, makes it unavailable to other applications on the machine.

To create a pool of wired memory on these UNIX platforms only, specify the -iqwmem command-line switch, indicating the number of MB of wired memory. (You must be user root to set -iqwmem, except on Solaris.) On 64-bit platforms, the only upper limit on -iqwmem is the physical memory on the machine.

For example, on a machine with 14GB of memory, you may be able to set aside 10GB of wired memory. To do so, you specify:
-iqwmem 10000
Note: Use -iqwmem only if you have enough memory to dedicate the amount you specify for this purpose. Otherwise, you can cause serious performance degradation.
  • On Solaris, -iqwmem always provides wired memory.

  • On HP, -iqwmem provides wired memory if you start the server as root. It provides unwired memory if you are not root when you start the server. This behavior may change in a future version.

Impact of Other Applications and Databases

Server memory comes out of a pool of memory used by all applications and databases. If you try to run multiple servers or multiple databases on the same machine at the same time, or if you have other applications running, you may need to reduce the amount of memory your server requests.

You can also issue the UNIX command ipcs -mb to see the actual number of segments.

Troubleshooting HP Memory Issues

On HP-UX, check the value of the maxdsiz_64bit kernel parameter. This parameter restricts the amount of virtual memory available to Sybase IQ on 64-bit HP processors. See your Installation and Configuration Guide for the recommended value.

Related concepts
Paging Increases Available Memory
Utilities to Monitor Swapping
Server Memory
Manage Buffer Caches
Determine the Sizes of the Buffer Caches
Set the Buffer Cache Sizes
Specify the Page Size
Optimize for Large Numbers of Users