Memory Overcommitment?

[jose_maria_gonz]

Hi team,

I have been told by a "trusting source" at Microsoft that the Memory overcommitment in VMware ESX should not be used. It appears that it was mentioned in a VMware KB note as well.

Do you know if this statement is true or if there is a VMwar KB note where it says not to use it in production?

What is the VMware official response around Memory overcommitment in VI3 farms in production?

Rgds,

J.

[mcowger]

Thats BS.

You shouldn't overcommit to the point you are swapping, but not overcommitting at all is just ignorant. Otherwise whats the point of TPS?

--Matt

[aldikan]

I agree with Matt,

I think that ability to overcommit is the fundamental VMware approach. There are limits however, so VMs should be monitored for bottlenecks..:D

[vmroyale]

Agree with the previous posts indeed.

There is a great blog entry on this topic at: http://blogs.vmware.com/virtualreality/2008/10/memory-overcomm.html

[TCronin]

Would you really expect them to say that a feature that they can not get working in their virtualization product is production ready? We have been using memory overcommitment in production since 2004, and to great advantage. We have over 1500 guests in production and 99% of the time they run on hosts that are memory overcommited.

[jose_maria_gonz]

Hi team,

I agree with you all guys but the point is that according to "them" apparently there is a VMware KB note where it says not to use memory overcommitment in production!!!.

Is that true? I doubt it but just want to make sure about it to come back to them on this.

Thanking you in advance,

Rgds,

J.

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El Blog de Virtualizacion en Español

http://josemariagonzalez.es

[vmroyale]

Ask "them" to produce said document.

[depping]

No clue which KB article they are referring to. Ask them, they seem to know it... And while you're at it, ask them for their interpretation of "memory overcommitment". are they talking about swapping? balloon driver? page sharing?

Duncan

Blogging: http://www.yellow-bricks.com

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[TomHowarth]

Ask the Redmond boys to product the link to the said KB article. this is just another bought of Fud from MS, Memory overcommit has been part of the Vmware arsenal for a long time. it works and it used by many an enterprise in production.

TPS is an amazing memory saver, for example.

Tom Howarth

VMware Communities User Moderator

[jose_maria_gonz]

Hi team,

As you suggested I have asked them to send me the link.

“Avoid high memory overcommitment. Make sure the host has more memory than the total amount of memory that will be used by ESX plus the sum of the working set sizes that will be used by all the virtual machines.”

As you can see, "avoid high memory overcommitment" is an statement far from “VMware does not recommend to use memory overcommitment in production”

Thank you all for your help on this. much appreciated.

Rgds,

J.

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El Blog de Virtualizacion en Español

[depping]

I think the keyword in this phrase is "HIGH", in other words make sure it will not start swapping cause this will cost you performance

MS definitely has a nice way of twisting the facts and figures,

Duncan

Blogging: http://www.yellow-bricks.com

If you find this information useful, please award points for "correct" or "helpful".

[TomHowarth]

As Duncan says the Key word is HIGH, I have regularly overcommitted by 20% with no adverse effects, however to be truthful, machines are so powerful now and have buckets full of memory, I have found that recently my issue point has in reality been IO not Memory or CPU

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Tom Howarth

VMware Communities User Moderator