Enabling EVC with no VM Downtime

[alanrenouf]

I was just wondering if anyone was able to get EVC working without shutting down the VM's ?

I am trying to move hosts to a new EVC enabled cluster with no luck.

This didn't work either: http://communities.vmware.com/thread/201677 I got complaints about CPU architecture. I'm assuming this is because EVC changes the mask and wonder how this worked for other people.

Thanks

Alan

[AndreTheGiant]

If the source machine has a recent CPU is not possible migrate the VMs to a EVC cluster.

Remeber that EVC will "cut off" some CPU feature (for exemple last extension of SSE) to normalize all the CPU.

For this reason is not possibile to do Vmotion from a "new" CPU to a "old" one.

Andrea

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[alanrenouf]

Thanks, I just wasn't sure how people got this working like the blog below:

http://www.gabesvirtualworld.com/?p=101

Alan

[AndreTheGiant]

The VM "compatibity" problem could be real. But at this time I never got this problem.

Probably only very old application have this issue.

Andrea

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[MikeS1983]

Hi,

This method will depend on how much redundancy you have within you hosts. Here is how I did it:

5 host cluster which once EVC was enabled will be a 6 host cluster. Intel Zeon 53xx and Intel Zeon 54xx was causing me problems and therefore needed EVC working.

1) Put one of the existing live hosts into maintenace mode and remove from cluster.

2) Create new EVC enabled cluster with new host and host just removed from live cluster.

3) Migrate enough VM's to new cluster so I can put another host into maintenance mode and remove from live cluster then add to new cluster. This was the stage I thought would fail due to CPU masking issues, but it work fine.

4) Repeat until all VM's and hosts are in new cluster.

5) Recreate resource pools and configure cluster. (HA/DRS)

I hope this helps others. Any questions please ask.

Mike.

[alanrenouf]

Further investigation has shown that some guests will VMotion over to the new host which is now in an EVC cluster but other guests will throw a CPU incompatible message, these are the same OS !

If this is a host enabled feature which effectively dumbs down the CPU why can I VMotion some VMs and not others ?

Thanks

Alan

[kjb007]

The problem here is that it depends on which host where the vm was actually powered on. When that vm powered on, it "saw" the features enabled on that host, and will continue to see those features as available, whether it uses them or not. This leads me to believe that you may not also have all of the features consistent in the BIOS across all your hosts. Check NX/execute disable, this is most likely the culprint. One some hosts, it is probably on, where on others it is off. One other thing you can do is to go to the evc field in your cluster settings, it will tell you whether some hosts are incompatible. These are most likely the ones where settings are inconsistent, as EVC requires VT and Execute Disable turned on.

-KjB

VMware vExpert

[MikeS1983]

Hi Alan,

Can you confirm that VT and XD are enabled in the BIOS on the hosts in the new EVC cluster? These have to be enabled when EVC is first enabled, but may have been disabled somehow. I had this issue during a BIOS upgrade.

Mike.

[alanrenouf]

I have checked these using the tool from run-virtual and all looks the same for the servers (attached image) the first two are in the cluster without EVC enabled and the second two are in a cluster with EVC enabled.

[MikeS1983]

Hi Alan,

I've seen your attachment. Have you checked in the BIOS to see if these settings are correct? I myself use PE2950's and to ensure complete Vmotion compatability even with EVC enabled I had to enable VT (virtualization technology) and XD (Execute Disable).

Mike.

[alanrenouf]

I double checked this and it is definately enabled on the hosts, they also worked fine when in the same cluster so cant be that.

Its only some of the guests that will not migrate, others will move absolutly fine, I don't understand what could be set on the guests ?

Thanks

Alan

[MikeS1983]

I'm not sure this will matter, but do the guests all have VMtools installed and if so are they at the latest version?

[MikeS1983]

Hi ,

Are the VM's that won't migrate on the same host?

Wether or not this will work I don't know, but I would try restarting the VC agents on the host or hosts where the VM's will not migrate from.

Firstly run "service vmware-vpxa restart" followed by "service mgmt-vmware restart" on the hosts. Then restart the Virtual Centre service on the VC server.

Hope this helps.

[AndreTheGiant]

Its only some of the guests that will not migrate, others will move absolutly fine, I don't understand what could be set on the guests ?

Sure that is an EVC problem?

Could also be a more simple problem, like a local resource (CD ISO, serial, vmdk not on shared storage, snapshot, ...)

Andre

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[alanrenouf]

No they are on two hosts, some of the vms on each host will migrate, others will not. I have restarted the management services just for fun but still the same issue

Thanks for all your help.

Alan

[alanrenouf]

Its only some of the guests that will not migrate, others will move absolutly fine, I don't understand what could be set on the guests ?Sure that is an EVC problem?

Could also be a more simple problem, like a local resource (CD ISO, serial, vmdk not on shared storage, snapshot, ...)

Andre

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They can still migrate between the hosts in the cluster so im sure its not a simple problem, thanks though.

[alanrenouf]

Anyone else have any ideas or are you all busy installing vSphere Thanks for everyones help so far.[http://virtu-al.net]

[MikeS1983]

I wish I was installing vsphere!!!!! I know it might seem a bit drastic, but have you tried rebuilding one of the hosts and migrating off the rebuilt host to see if this makes a difference? Or disconnecting/removing and re adding the host into VC?

I realise some of your vm's migrate ok and others don't which would suggest a vm issue and not a host issue, but I'm currently out of ideas.

[alanrenouf]

Thanks, tried the disconnect/reconnect but still the same thing, these hosts were only built recently so shouldnt be that.

I wonder if VMware will support this or if they will say NO, you have to power them off and move them ?

Might just have to make a support call

Alan

[MikeS1983]

OK.

Let me know of any developments. I'm interested to see what the issue is.

Also I'll let you know if I have any ideas.

Mike.