How EVC plays a role in Vmotion between AMD and Intel- Which myth is right ?

[manishisarda]

Hi,

I am bit confused between what EVC can do. got 2 set of different answers

1. VMware Enhanced VMotion Compatibility (EVC)-available in VMware Infrastructure 3 beginning with version 3.5 Update 2-facilitates VMotion between different CPU generations, taking advantage of Intel Flex Migration and AMD‐V Extended Migration technologies.To minimize exacerbation of the compatibility problem with time, VMware has worked with CPU vendors to facilitate live migration of virtual machines across different CPU revisions.

Referance

2. EVC does not allow for VMotion between Intel and AMD... It's for allowing VMotion between older (to a degree) processor families to new ones (i.e. from Rev. E/F Opterons to Barcelona). Unfortunately, I think the 380 G3 would be running a processor family too old for use with EVC, assuming the destination servers were Intel-based..

which one is right ?

Thanks

Manish

[Yattong]

Hey

Both are correct.

You have to read the 1st statement very carefully.

1. VMware Enhanced VMotion Compatibility (EVC)-available in VMware Infrastructure 3 beginning with version 3.5 Update 2-facilitates VMotion between different CPU generations, taking advantage of Intel Flex Migration and AMD‐V Extended Migration technologies.To minimize exacerbation of the compatibility problem with time, VMware has worked with CPU vendors to facilitate live migration of virtual machines across different CPU revisions.

"Between different CPU generations" not between different CPU manufacturers.

2. EVC does not allow for VMotion between Intel and AMD... It's for allowing VMotion between older (to a degree) processor families to new ones (i.e. from Rev. E/F Opterons to Barcelona). Unfortunately, I think the 380 G3 would be running a processor family too old for use with EVC, assuming the destination servers were Intel-based..

This is correct, however Im not sure what you're running inside the DL380 so I cant really comment.

More info on EVC

www.vmware.com/files/pdf/vmotion_info_guide.pdf

http://communities.vmware.com/message/1034644;jsessionid=8DFC7587F290D4628408A96C175D3EB5

http://communities.vmware.com/message/1069831;jsessionid=2EF5284E6E14E1B69B95BB216BEBF75A

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[manishisarda]

Before reading the referance link, i was clear that EVC can not vmotion vms from AMD to Intel and viceversa. The reference link made me think on that .

And if whatever u r saying is right, then what exactly VMware wants to achievt with EVC, i mean to say what was missing in normal vmotion.

Thnaks

[Yattong]

Hey,

You were unable to vmotion VM's where there are differences in CPU family, not just Manufacturer.

So for example, you could not vmotion a VM from an IntelP4 host to and Intel Dual Core host.

What EVC allows, along with the new CPU technology that is available is the compatibilty amongst CPU families within the same Manufacturer.

Again, you'll have to check the docs to see what CPU families this will encompass and whether it will help you or not.

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[JonRoderick]

My 2 pence - if I understand it correctly, what EVC does is check the CPU capabilities of a host before it joins the cluster and takes care of modifying the CPU masks applied to VMs to enable vmotion between different CPU generations. This is why hosts cannot be added to the cluster with VMs running.

Before this, everything had to be done manually on the VM itself and I don't think that was even supported (or is even now).

Cheers.

[Yattong · Accepted solution]

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