IBM 170 Servers Manual page 170

The following is an example of how to issue the command:
CHGATR OBJ( name of object) ATR(*MAINSTGOPT) VALUE(*NORMAL, *MINIMIZE, or
*DYNAMIC)
The chart below depicts V5R3-based paging curve measurements performed with the following settings
for the mail databases: *NORMAL, *MINIMIZE, and *DYNAMIC.
V5R3 Main Storage Options Fault Rates
5
4
3
2
1
0
60775040
V5R3 *DYNAMIC
Figure 11.4 V5R3 Main Storage Options on a Power4 System - Page Fault Rates
In figures 11.4 and 11.5, results are shown for tests that were performed with a Mail and Calendaring
Users workload and various settings for Main Storage Option. The tests started with the users running at
steady state with adequate main storage resource available, and then the main storage available to the
*base pool containing the Domino servers was gradually reduced The tests used an NSF Buffer Pool Size
of 300MB with multiple Domino partitions.
Notice in Figure 11.4 above that as the base pool decreased in size (moving to the right on the chart), the
page faulting increased for all settings of main storage option. Using the *DYNAMIC and *NORMAL
attributes provided the lowest fault rates when memory was most abundant at the left side of the curve.
Moving to the right on the chart as main storage became more constrained, it shows that less page faulting
takes place with the *MINIMIZE storage option compared to the other two options. Less page faulting
will generally provide better performance.
In V5R3 the performance of *DYNAMIC has been improved and provides a better improvement for
faulting rates as compared to *NORMAL than was the case in V5R2. When running with *DYNAMIC
in V5R2, information about how the file is being accessed is accumulated for the open instance and
adjustments are made for that file based on that data. But when the file is closed and reopened, the
algorithm essentially needs to start over. V5R3 includes improvements to keep track of the history of the
file access information over open/close instances.
IBM i 6.1 Performance Capabilities Reference - January/April/October 2008
©
Copyright IBM Corp. 2008
47026568 36388264
BASE POOL SIZE(KB)
V5R3 *NORMAL
Chapter 11 - Domino
28156548 21787000
V5R3 *MINIMIZE
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