Cache

The Set button in the Cache section lets the administrator view and modify the memory cache settings of the relational database server.

Changes to these settings affect all of the relational databases that the database server manages. The changes do not take effect until the database server is restarted.

The database cache is an area of memory used by the database server to store database pages for repeated fast access. The more pages that are accessible in the cache, the fewer times the database server needs to read data from disk.

Reading data from disk is a slow operation and the amount of cache available is often a key factor in determining performance. The database cache is automatically resized as needed.

The cache grows when the database server can usefully use more, as long as memory is available. The cache shrinks when other applications require cache memory so that the database server does not unduly affect other applications on the system.

The NetBackup Database Cache settings dialog uses memory cache settings to control the size of the database cache.

Minimum cache size	Sets the minimum cache size as a lower limit to automatic cache resizing. (This setting represents the -cl option in the server.conf file.)
Initial cache size	Sets the initial memory reserved for caching database pages and other server information. (This setting represents the -c option in the server.conf file.)
Maximum cache size	Sets the maximum cache size as an upper limit to automatic cache growth. (This setting represents the -ch option in the server.conf file.) If the settings are too large, the database server may not start.

Configure these settings in this dialog or in the server.conf file. The database server reads the file when it is started.

Table 1-1 Database Cache Settings


Option	Minimum cache size	Initial cache size	Maximum cache size
Current	As configured	As configured	As configured
Small	25MB (50MB with BMR)	25MB (50MB with BMR)	500MB (750MB with BMR)
Medium	200MB (400MB with BMR)	200MB (400MB with BMR)	750MB (850MB with BMR)
Large	500MB (750MB with BMR)	500MB (750MB with BMR)	1000MB (1000MB with BMR)
Custom	Configurable	Configurable	Configurable