Formula for Calculating Memory and Processor Sizeing for VI3

[deepu_cherian]

Hi Everyone,

I have two questions. Answers will be highly appreciated. We are planning to implement a new VI3 Environment would like to know below details.

On ESx 2.5 I used the Memory Sizeing formula given below to calculate the memory.

A + 24 + (54 xB) + ( C xB) < D

A= memory allocated for service console ( ESX Server)

B= Number of VM's

C= Max memory allocated to each VM

D= Amount of Physical Ram on ESX Server

24= Base rek for VMkernal

54= Overhead for each VM

Is this calculation still Valid for VI3?

Is there a similar calculation for Processor? if so what is it?

How processor Sizeing calculated?

Any reply, links etc will be appreciated.

Thanks

Deepu.

deepucherian@gmail.com

609-282-7091

[esiebert7625]

I would count on 800MB for the SC (default is 272MB but it is usually recommended to increase this to the max). ESX3 has alot of memory saving techniques so you can definitely over-commit memory on your VM's.

These links talk about memory management...

The Role of Memory in ESX Server 3 - http://www.vmware.com/pdf/esx3_memory.pdf

Memory resource management in Vmware ESX Server - http://www.vmware.com/pdf/usenix_resource_mgmt.pdf

You might check out the Resource Management Guide, starting on page 128 it has info on VM memory overhead and a chart.

Resource Management Guide - http://www.vmware.com/pdf/vi3_301_201_resource_mgmt.pdf

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Thanks, Eric

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[deepu_cherian]

Eric,

Thanks for the Quick response....

What I'm really looking here to find formula or some sort of planning for processor.

As an example,

I'm planning to put 10 VM's ( 2k3 App servers) with 32GB memory and 2 Quad core processor on my single Host. Di i need to go for 4 Quad core?

if so I have to change my server model and cost ?

How do I know how much processing power my each VM gets?

Above is a formula for memory calculation. Are you aware of any such calculation for processor based on Speed? If now How do I plan my processor power?

[esiebert7625]

It's really hard to use a formula for this because the cpu & memory requirements will vary for each VM based on the applications they run. A general rule of thumb is 4 VM's per processor core, of course this will vary based on the VM's, you might be able to go up to 8 VM's per core on VM's that do not need alot of resources. This is something capacity planner was built for, it installs on physical servers and measures hardware statistics so you know how to plan your VMware environment properly. These additional links might help you...

VMware ESX Server: A comprehensive guide to how ESX virtualizes HP ProLiant servers - http://h20331.www2.hp.com/ActiveAnswers/downloads/vmwareESXserver_virtualize_ProLiant_1005.pdf

HP ProLiant server sizer for VMware ESX Server - http://h71019.www7.hp.com/activeanswers/cache/120132-0-0-0-121.html

IT Consolidation using VMware CapacityPlanner on HP ProLiant servers - http://h71019.www7.hp.com/ActiveAnswers/cache/70314-0-0-225-121.html?jumpid=reg_R1002_USEN

VMware Capacity Planner Overview - http://www.vmware-tsx.com/download.php?asset_id=35

Production Consolidation using VMware and the AMD Opteron Processor - http://download3.vmware.com/vmworld/2006/adc9743.pdf

IBM Insights in Sizing Hardware for Virtualization - http://download3.vmware.com/vmworld/2006/tac4057.pdf

[Ken_Cline]

Hi Deepu,

The formula is going to be very similar for VI3. I've not seen the exact overhead values, but it's going to be close. I would recommend that you not try to make it so much a science - especially if you've got a multi-host environment and are using DRS (or just manually VMotioning guests around).

The best approach is typically to proactively monitor your environment and set a threshold for when you need to add more resources.

As for CPU utilization - if you've got existing physical servers, use perfmon or similar to track the current CPU utilization. Then apply that value to the virtual host to get an approximation of what the workload would be.

You can use the HP online HP ProLiant server sizer for VMware ESX Server[/url] to get a good feel for what you'll need.