Intel 7xx Servers, 170 Servers, AS/400 RISC Server manual Thousands

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
POOL FAULTS/SEC		4
	Thousands	3
		2
BASE		1
		0
		60775040	47026568	36388264	28156548	21787000

BASE POOL SIZE(KB)

V5R3 *DYNAMIC V5R3 *NORMAL V5R3 *MINIMIZE

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	Chapter 11 - Domino	170