DOMINO AND DB2

Setting the size of the buffer pool to improve performance
Buffer pools are allocated as a number of shared RAM segments on the database server. Database records are read and updated in the buffer pool area of memory. If the buffer pool is large enough to keep required data in memory, less disk activity occurs. If the buffer pool is not large enough to keep required data in memory, the adverse affect on overall database performance can be severe. Buffer pool size is the first DB2 parameter to check if performance is poor.

In an IBM® Lotus® Domino™ and IBM® DB2 Universal Database™ Enterprise Server Edition configuration, the buffer pool can become quite large. To improve performance, you can increase the amount of memory allotted to the buffer pool for the initial DB2 database that was created when you installed Domino and DB2. By default, the DB2 database that is automatically created is named DOMINO, unless you specified a different database name. The buffer pool has the same name as the initial database.

To determine how much memory can be allotted for the buffer pool, subtract the amount of memory consumed from the total amount of memory. Assign the difference to the buffer pool. Buffer pool sizes are specified in numbers of pages, which are fixed blocks of data read from and written to disk. For each buffer pool, the size consumed is the page size (in KB) times the buffer pool size. The graphic shown in Step 5 of the procedure contains sample buffer pool values.

Use the DB2 Control Center to locate the Buffer Pool configuration parameter for your initial DB2 database.

1. Open the DB2 Control Center.

2. Click All Databases.

3. Locate the initial DB2 database you created, and then open the database. If you did not change the default database name, the name is DOMINO.

4. Locate and open the buffer pools folder.

5. Select the buffer pool, right-click the mouse, and then click Alter. The Alter Buffer Pool dialog box appears.


6. Assign the largest amount of memory to the DOMINO buffer pool. Assign lesser amounts of memory, such as 12K - 16K, to each of the other buffer pools.

7. Click OK.

Note For detailed information about modifying configuration parameters in DB2, see the DB2 Information Center at http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.ibm.db2.udb.doc/core/db2idxA.htm.

See also