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than or equal to 98%. To check the cache hit percentage, use the query db f=d
command, as shown in Example 15-17. This shows that our cache hit
percentage is 99.89%, which is fine.
Example 15-17 query db f=d
tsm: LOCHNESS_SERVER1>q db format=detail
Available Space (MB): 2,024
Assigned Capacity (MB): 2,024
Maximum Extension (MB): 0
Maximum Reduction (MB): 1,616
Page Size (bytes): 4,096
Total Usable Pages: 518,144
Physical Volumes: 3
Buffer Pool Pages: 65,280
Total Buffer Requests: 37,804
Backup in Progress?: No
Type of Backup In Progress:
Incrementals Since Last Full: 2
Changed Since Last Backup (MB): 113.02
Percentage Changed: 27.64
Last Complete Backup Date/Time: 02/21/2006 17:12:20
Estimate of Recoverable Space (MB): 0
Last Estimate of Recoverable Space (MB): 02/17/2006 12:09:21
Increasing the BUFPOOLSIZE parameter can improve the performance of many
Tivoli Storage Manager server functions, such as multi-client backup, storage
pool migration and backup, expiration processing, and move data. If the cache
hit percentage is lower than 98%, increase the BUFPOOLSIZE value in the
server options file. For most servers, we recommend starting with a value of
32768, which equals 8192 database pages. If you have enough memory,
increase in 1 MB increments. A cache hit percentage greater than 98% indicates
that the proper BUFPOOLSIZE has been reached. However, continuing to raise
BUFPOOLSIZE beyond that level may still be helpful. While increasing
BUFPOOLSIZE, take care not to cause paging in the virtual memory system.
Monitor system memory usage to check for any increased paging after changing
the BUFPOOLSIZE.
Used Pages: 104,680
Pct Util: 20.2
Max. Pct Util: 20.2
Cache Hit Pct.: 99.89
Cache Wait Pct.: 0.00
Chapter 15. Performance considerations
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