Which guest OS supports hot remove of CPU?

[rickardnobel]

I have seen that there is a possibility to configure "Hot remove CPU" on a VM. However, on Windows 2008 that option is greyed out, which I guess means that Win2008 does not support hot remove of CPUs. However, I am curious, what guest operating system does support this? Linux? Or Solaris?

[vmroyale]

Hello.

I have seen that there is a possibility to configure "Hot remove CPU" on a VM. However, on Windows 2008 that option is greyed out, which I guess means that Win2008 does not support hot remove of CPUs. However, I am curious, what guest operating system does support this? Linux? Or Solaris?

I've been using Jason Boche's blog entry for the Windows systems. I think the Linux distros just needed to be on a certain kernel.

Good Luck!

[rickardnobel]

Hello, and thank you for your reply. The link did however just confirm that Windows does not support Hot Remove of CPUs, but not on which operating systems this could be done. I am not actually planning to do it, it would just be interesting to know.

(Imagine doing this on a physical server....) :smileyhappy:

[Texiwill]

Hello,

I have yet to find one that supports this functionality. For Linux I would assume there needs to be a new driver for the kernel that as of now, does not yet exists.

I believe that VMware added the functionality planning for the future... Or they may know of an OS that does support it...

Best regards,
Edward L. Haletky VMware Communities User Moderator, VMware vExpert 2009, 2010

Now Available: 'VMware vSphere(TM) and Virtual Infrastructure Security'[/url]

Also available 'VMWare ESX Server in the Enterprise'[/url]

Blogging: The Virtualization Practice[/url]|Blue Gears[/url]|TechTarget[/url]|Network World[/url]

Podcast: Virtualization Security Round Table Podcast[/url]|Twitter: Texiwll[/url]

[rickardnobel]

I believe that VMware added the functionality planning for the future... Or they may know of an OS that does support it...

If they have implemented the feature I guess they must suspect that at least SOME guest could use it. :smileyhappy:

By the way, ESX and ESXi, do they support hot add of memory and CPUs on their own hardware?

[Texiwill]

Hello,

Never Tried.... ESX in ESX is not yet officially supported.

Best regards,
Edward L. Haletky VMware Communities User Moderator, VMware vExpert 2009, 2010

Now Available: 'VMware vSphere(TM) and Virtual Infrastructure Security'[/url]

Also available 'VMWare ESX Server in the Enterprise'[/url]

Blogging: The Virtualization Practice[/url]|Blue Gears[/url]|TechTarget[/url]|Network World[/url]

Podcast: Virtualization Security Round Table Podcast[/url]|Twitter: Texiwll[/url]

[rickardnobel]

Never Tried.... ESX in ESX is not yet officially supported.

(I think I have tried running ESX as a VM inside another ESX and it did work.)

However, what I meant was actually if ESX supports hardware hot add of cpu/ram in the real physical server the host is running on?

[Texiwill]

Hello,

(I think I have tried running ESX as a VM inside another ESX and it did work.)

It will work, it is not supported, etc.

However, what I meant was actually if ESX supports hardware hot add of cpu/ram in the real physical server the host is running on?

Not to my knowledge.

Best regards,
Edward L. Haletky VMware Communities User Moderator, VMware vExpert 2009, 2010

Now Available: 'VMware vSphere(TM) and Virtual Infrastructure Security'[/url]

Also available 'VMWare ESX Server in the Enterprise'[/url]

Blogging: The Virtualization Practice[/url]|Blue Gears[/url]|TechTarget[/url]|Network World[/url]

Podcast: Virtualization Security Round Table Podcast[/url]|Twitter: Texiwll[/url]

[rickardnobel]

Thanks!

But we do not know if there actually is any guest operating that supports hot remove of CPU?

[Texiwill]

Hello,

That is correct. I have yet to find one and I have been through all the official ones listed in the vSphere Client. The closest I found was a generic linux, but if there is no driver that supports this then it is not doable. At the moment I do not even know of a driver for Linux that supports hotremove of a CPU. Hot add of memory, yes but not hot remove of a CPU.

Best regards,
Edward L. Haletky VMware Communities User Moderator, VMware vExpert 2009, 2010

Now Available: 'VMware vSphere(TM) and Virtual Infrastructure Security'[/url]

Also available 'VMWare ESX Server in the Enterprise'[/url]

Blogging: The Virtualization Practice[/url]|Blue Gears[/url]|TechTarget[/url]|Network World[/url]

Podcast: Virtualization Security Round Table Podcast[/url]|Twitter: Texiwll[/url]

[rickardnobel]

Thanks for your help! It would just be interesting to test and see this.

[FredPeterson]

I'm extremely surprised the answer to this isn't easy to come by. In order for hot remove of CPU to even begin to function correctly, there must exist a service that the operating system runs that can flush the CPU from the kernel before the physical hardware can be removed. That implies a common set of APIs that can be referenced by the VMware Tools so that regardless of which OS, it would work.

To me that means yes, VMware should know what OS' do and do not support it right now and have that published.

[rickardnobel]

To me that means yes, VMware should know what OS' do and do not support it right now and have that published.

I am also a bit surprised that this is not know, but to find out I did some manual work to find out.

Depending on the selected guest operating system the selection on the VM:s option tab "Memory/CPU Hotplug" will either not be visible at all or only allow certain combination. It is easy to see if switching between setting the guest on the General Option to Windows 2003 standard = not visible, Windows 2003 Enterprise, visible but only RAM hotadd, Window 2008 = CPU and RAM hotadd.

So by doing some testing I thought I should be able to spot this by creating a dummy VM and testing different guest operating systems and watch the changes on the "Memory/CPU Hotplug".

By these tests I have observed that no version of Solaris, Netware, Freebsd, OS/2, SCO, RH Linux 5, Suse Enterprise, Debian, Asianux or Ubuntu has the CPU hot remove option. Both 32 and 64 bits version tested. Not available on the more generic "Other 64 bit" guest or "Other Linux 2.4x or 2.6x" guest either.

I already know no Windows version is capable of this, so the conclusion seems to be that no guest operating system at the moment actually supports this, and that this option is useless at the moment, but could perhaps be introduced in a later vSphere release.

[rickardnobel]

No guest OS seems to support this today.

[bluecollarit]

is hot add of cpu and memory supported

[FredPeterson]

http://www.boche.net/blog/index.php/2009/05/10/vsphere-memory-hot-add-cpu-hot-plug/