Should the default setting for IOs be used for VMware's round robin NMP?

Thanks. This is just what I wanted.

Our team wrote a white paper on this topic that can be found at the below link on Powerlink that discusses the ins and outs of changing this parameter. In general you will see increased performance by lowering it to 1 and rarely if ever decreased performance but there are consequences of this on Symmetrix FA load as well as a few other things. I highly recommend reading this paper before making any changes.

http://powerlink.emc.com/km/live1/en_US/Offering_Technical/White_Paper/h8119-tuning-vmware-symmetrix-wp.pdf

Thanks

Cody

Cody,

there is no mentioning of DMX platform, do these recommendations apply to DMX3/4 as well or VMAX only ?

Thanks

Hi,

We did the testing  and analysis on a VMAX by setting the nmp roundrobin i/o operational limit parameter to 1. Having said that I do not see why you cannot set it to 1 when using NMP on DMX/DMX4 arrays. The setting is on the ESX host and you should be OK setting it to 1 on DMX/DMX4. Hope this helps.

Thanks,
Narasimha

Was there ever a comparison done between PowerPath and NMP round robin?  Are there certain scenarios that make one or the other a no-brainer? Or do  they give fairly equivalent performance, availability, etc.?

getting "Access denied"

This is an internal only presentation. If there is a public version that can be shared, I will post.

I'm getting an access denied from your link too.

For those of you without access to Powerlink, here is the EMC.com public link to the aforementioned white paper concerning tuning the IOPS parameter:

http://www.emc.com/collateral/hardware/white-papers/h8119-tuning-vmware-symmetrix-wp.pdf

Thanks!

Cody

see the following posts:

http://virtualgeek.typepad.com/virtual_geek/2010/03/understanding-more-about-nmp-rr-and-iooperationslimit1.html

http://www.yellow-bricks.com/2010/03/30/whats-the-point-of-setting-iops1/

in my opinion since changing it to 1 IO has shown improvement (even if its small) its worth the change