VS4 NUMA nodes imbalance

[Albatross]

Hi Folks,

Recently we've found this message after a successful ESX4 installation:

"Signficant imbalance between NUMA nodes detected. Performance may be impacted."

Server is a BL460c G6, with two CPUs and a dissimilar amount of ram (3x2GB and 1x4GB).

Is there a way to disable NUMA funcionality within the RBSU or boot-time parameters?

Thanks a lot for your responses,

Albatross

[Uwe Zessin]

From my understanding, NO, because the memory controller is embedded in the CPU - there is no shared memory bus: if processor A wants data from memory that is connected to processor B it uses the 'QuickPath Interconnect' between proc A+B. B fetches the data from its local memory and sends it across the QPI to A.

[Daniel Bowers · Accepted solution]

You can disable NUMA within RBSU on the BL460c G6 by setting "Enable Node Interleaving" within the "Advanced Options / Advanced Performance Tuning Options" menu to "Enable".

This will cause the BIOS to alternate between the two processors' memory when building the system memory map.

I'm not sure how VS4 will perform, though.

[ilayy]

hi experts
does the g6 line if blade system use NUMA or advanced ecc for memory configuration?

[Albatross]

Hi ilayy,

NUMA (Non-Uniform Memory Access) is a technique to address and use memory distributed in different processors/memory controllers within the same physical system.

ECC (eror checking and correcting) allows the memory subsystem to detect memory errors and instruct the system to either correct the error or halt the system to prevent data loss/corruption (advanced ECC in the 460c G6)

The BL460c G6 supports both technologies.

Hope it helps,

[oczkov]

Hello Guys,

Seems like you looked for this article:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1018754

Note: If one of the physical RAM modules is damaged or faulty, it will also cause an imbalance and thus causing the error to be thrown in the ESX console.

bl460 g6 is non-NUMA, I guess and the imbalance is caused by failing DIMM or DIMMs.

Regards,
oczkov

[Ali]

Hi There,

As per g6 memory rules, you can install different size memory accross processor but when it comes to ESX 4 it looks for similar memory configuration for both the processors and you will get this message...

disabling it from RBSU is one option and getting the patch from vmware for this issue is a permanent solution.

thanks,
Aftab