On Solaris UFS and Windows file systems only, you can control whether file system buffering is turned on or off. Turning off file system buffering saves a data copy from the file system buffer cache to the main IQ buffer cache. Usually, doing so reduces paging, and therefore improves performance. Be aware of one exception: If the IQ page size for the database is less than the file system's block size (typically only in the case in testing situations) turning off file system buffering may decrease performance, especially during multiuser operation.
File system buffering is turned off by default for newly created Sybase IQ databases.
To disable file system buffering for existing databases, issue the following statement:
SET OPTION "PUBLIC".OS_FILE_CACHE_BUFFERING = OFF
You can only set this option for the PUBLIC group. You must shut down the database and restart it for the change to take effect.
Solaris does not have a kernel parameter to constrain
the size of its file system buffer cache. Over time, the file system
buffer cache grows and displaces the IQ buffer cache pages, leading
to excess operating system paging activity and reduced Sybase IQ performance.
Windows can bias the paging algorithms to favor applications at the expense of the file system. This bias is recommended for Sybase IQ performance. See Chapter 7, “Tuning Servers on Windows Systems” for details.
