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VMware Hot-Add Memory/CPU Support

I've been asked to take a look into the Hot-Add Memory and CPU features which are available with vSphere 4. The concept seems pretty useful and straight forward, but what isn't is the list of Operating Systems that support these features. There doesn't seem to be a definitive list. Either that, or I should have gone to Specsavers?

I've had a look around and I can find two KB articles from VMware: Here, and Here which talk about using Hot-Add on Linux OS's. Another VMware document focused on Microsoft: VMware Guest/Host OS Compatibility Guide There is Jason Boche's great article which he researched and tested himself, And Daniel Eason's summary on Hot-Add.

From these different articles I have taken all of the information and produced the following table which in theory should be all of the OS's which support VMware Hot-Add Memory/CPU.

Operating System

Service Pack

Hot-Add Memory

Hot-Add CPU

Windows Server 2008 Datacenter Edition  x64

 

 

 


R2

Yes

Yes


SP2

Yes

Yes


SP1

Yes

Yes

Windows Server 2008 Datacenter Edition  x86





Unknown

Yes

No

Windows Server 2008 Enterprise Edition  x64





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Server 2008 Enterprise Edition x86





Unknown

Yes

No

Windows Server 2008 Standard Edition x64





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Server 2008 Standard Edition x86





Unknown

Yes

No

Windows Server 2008 Web Server x64





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Serve 2008 Essential Business Server Premium x64





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Server 2008 Essential Business Server Standard x64





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Server 2008 Small Business Server Premium





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Server 2008 Small Business Server Standard





R2

Yes

No


SP2

Yes

No


SP1

Yes

No

Windows Server 2003 Enterprise Edition  x64





Unknown

Yes

No

Windows Server 2003 Enterprise Edition  x86





Unknown

Yes

No

 

 



Do you know different? If you are aware of other OS's that can make use of these features, please leave a comment below.

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Simon Long

4 Comments

  • Hey Simon

    Based on that list, nobody will be using the hot add CPU feature then!! I remember when this first came out a colleague said “Windows would through a fit if you threw another CPU in while it was still running” and the list suggests they were right.

    I liked Scott Lowe's approach in his vsphere book. He has an application owner demanding 16GB, so he assigns the box 16GB and then puts a limit on it of 2GB. App owner is happy as he thinks he has 16GB and VM admin is happy as he has only given out 2GB. If it needs to be amended on the fly, well you just increase the limit, sort of like hot adding memory. Suppose you could do the same with vCPU's and number of clock cycles. Although this approach takes a little more thought and management if the server is important enought to need Hot Add then this approach would give you that zero downtime capability on OS's that are not supported currently.

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