vmo command can fail with the error "Unsupported attribute value" in environments without memory affinity

How To

Summary

In environments without memory affinity, vmo command can fail with the error "Unsupported attribute value" when you try to set a tunable value.
In these environments, memory affinity is usually disabled as the tunable "memory_affinity" is set to 0.
The failure can happen when you set other vmo tunables like, pgz_mode, pgz_lpgrow or pgz_num_workers.

Environment

AIX® 7200

Steps

When the "memory_affinity" tunable value is 0 on the LPAR, any attempt to change tunables like, pgz_mode, pgz_lpgrow or pgz_num_workers, using

vmo command can fail.

vmo command can fail with the following error message:

vmo: 1485-124 Error setting pgz_mode : Unsupported attribute value
vmo: 1485-124 Error setting pgz_num_workers : Unsupported attribute value
vmo: 1485-124 Error setting pgz_lpgrow : Unsupported attribute value

To over come the failure with vmo command, follow these steps:

1. Enable memory affinity by setting 'memory_affinity' tunable value to 1:

# vmo -r -o memory_affinity=1

Type "yes" when prompted. Then, the boot image is rebuilt.

For the tunable to take effect, reboot the machine.

Once the system is rebooted, it sets the tunables according to values in the file "/etc/tunables/nextboot".

2. In case they are not set to the required values, you can set them using the following command:

# vmo -p -o pgz_lpgrow=3 -o pgz_mode=3 -o pgz_num_workers=12

Additional Information

With memory affinity disabled, vmo command can be as follows:

#‌ vmo -p -o pgz_lpgrow=3 -o pgz_mode=3 -o pgz_num_workers=12

Setting pgz_mode to 3 in nextboot file
Modification to restricted tunable pgz_num_workers, confirmation required yes/no yes
Setting pgz_num_workers to 12 in nextboot file
Setting pgz_lpgrow to 3 in nextboot file
Warning: although the change concerns a dynamic tunable, bosboot should be run to optimally restore these settings at reboot
vmo: 1485-124 Error setting pgz_mode : Unsupported attribute value
vmo: 1485-124 Error setting pgz_num_workers : Unsupported attribute value
vmo: 1485-124 Error setting pgz_lpgrow : Unsupported attribute value

After you enable memory affinity by changing the memory_affinity tunable value to 1, vmo command output can be as follows:

$ vmo -p -o pgz_lpgrow=3 -o pgz_mode=3 -o pgz_num_workers=12
Setting pgz_mode to 3 in nextboot file
Modification to restricted tunable pgz_num_workers, confirmation required yes/no y
Setting pgz_num_workers to 12 in nextboot file
Setting pgz_lpgrow to 3 in nextboot file
Warning: although the change concerns a dynamic tunable, bosboot should be run to optimally restore these settings at reboot
Setting pgz_mode to 3
Setting pgz_num_workers to 12
Warning: a restricted tunable has been modified
Setting pgz_lpgrow to 3

Document Location

Worldwide

Operating System

AIX:All operating systems listed

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SWG10","label":"AIX"},"ARM Category":[{"code":"a8m0z000000cvzMAAQ","label":"Kernel->VMM"}],"ARM Case Number":"TS003507143","Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"All Version(s)","Line of Business":{"code":"LOB08","label":"Cognitive Systems"}}]

Product Synonym

AIX

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Document Information

Modified date:
15 September 2021

UID

ibm16238754

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