andremostert
Contributor
Contributor

Scaling physical CPU's to vCPU's

Guys,

I need some options and suggestion of real live environments.

We would like to scale up our environment and would like to know what best practises are being used on other sites.

What we have:

3x DL385G6 VMware cluster

2x P4500G2 SAN

To upscale we are thinking of adding more DL385's and installed more memory on all the servers. Also to upgrade the SAN with one more P4500 SAN tray. On the CPU side we would like to try and find out how much other people oversubscribe on there CPU's. Some guys recommend 4 VM's to one core and other 8 VM's per core. I know it all depends on what is hosted on the vm's. But if you use the usual suspects, Windows 2008 R2, Exchange, SQL and so on.

Any suggestion and feedback would be appreciated as I am trying to get as much feedback as possible.

Many thanks

Andre

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3 Replies
Tigerstolly
Enthusiast
Enthusiast

Possibly no "right" answer to this, only you have access to detailed metrics on your own workloads.

As an overall rule of thumb i've commonly seen 10:1 v to p cpu ratios with no problems, and have heard that other people go to 15:1

You just need to give it some thought, based on the usage patterns of your estate.

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Have happily run 15:1 (even more sometimes) - though it totally depends on the VM demands.

e.g. a whole bunch of Windows XP dekstops is never going to use the same resource as a handful of SQL servers?

Load them up and monitor your resource utilisation.

Always request as much as you reckon you can get away with, and always overspec.

Lastly, make sure you design your environment N+2, because expansion always happens and you are bound to need to bring hosts down at times for maintenance.

One day I will virtualise myself . . .
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andremostert
Contributor
Contributor

Great stuff guys this is very good information,

I also had some feedback from another mate and 6x DL360's with 46 servers running perfect only 9% CPU ulilization. I also confirmed that I can mix the HP DL385 G6 and G7 series. This vmotion problem was fixed in the new version of ESX4. You can also mix memory amounts as the vmware will balance it over all the nodes in the VMware cluster.

I am going to grow my cluster with new DL385G7's and add a extra shelf on the HP P4500G2 SAN.

Any one else have more information. The more experences we not down the more help it would be for people find the post.

Andre

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