Measuring the efficiency of EDM pools
You can use information in the Db2 statistics record to calculate the efficiency of the EDM skeleton pool, the EDM DBD cache, and the EDM statement cache.
Procedure
To measure the efficiency of the EDM pools:
- DBD HIT RATIO (%)
- CT HIT RATIO (%)
- PT HIT RATIO (%)
- STMT HIT RATIO (%)
These ratios for the EDM pool depend upon your location's workload. In most Db2 subsystems, a value of 80% or more is acceptable. This value means that at least 80% of the requests were satisfied without I/O.
The number of free pages is shown in FREE PAGES. For pools with stealable objects, if this value is more than 20% of the number of pages for the corresponding pools during peak periods, the EDM pool size is probably too large for that type of pool. In this case, you can reduce its size without affecting the efficiency ratios significantly.
EDM pools in the statistics report
The Db2 statistics record provides information on the EDM skeleton pool, the EDM DBD cache, and the EDM statement cache.
EDM POOL QUANTITY
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PAGES IN DBD POOL (ABOVE) 14625.00
HELD BY DBD 107.00
STEALABLE PAGES 0.00
FREE PAGES 14518.00
% PAGES IN USE 0.73
FAILS DUE TO DBD POOL FULL 0.00
PAGES IN STMT POOL (ABOVE) 262.1K
HELD BY STATEMENTS 207.00
FREE PAGES 261.9K
FAILS DUE TO STMT POOL FULL 0.00
PAGES IN SKEL POOL (ABOVE) 2560.00
HELD BY SKCT 2.00
HELD BY SKPT 12.00
STEALABLE PAGES 14.00
FREE PAGES 2546.00
% PAGES IN USE 0.00
FAILS DUE TO SKEL POOL FULL 0.00
DBD REQUESTS 599.3K
DBD NOT FOUND 0.00
DBD HIT RATIO (%) 100.00
CT REQUESTS 0.00
CT NOT FOUND 0.00
CT HIT RATIO (%) N/C
PT REQUESTS 2878.00
PT NOT FOUND 0.00
PT HIT RATIO (%) 100.00
PKG SEARCH NOT FOUND 0.00
PKG SEARCH NOT FOUND INSERT 0.00
PKG SEARCH NOT FOUND DELETE 0.00
STATEMENTS IN GLOBAL CACHE 48.00