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Asher_N
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How portable are our VMs?

I tun a typical small shop, 100 or so users.

In early 2007, I was facing an undersized, aging file server. was also loking at the incresing number of software that rely on HTTP to communicate and that most do not play well toghether. Getting a new physical machine for each is just insane, so I took the plung and bought a new server and installed ESX on it. Decent machine, a pair of Xeon 5160 dual core procs, 10GB RAM, a pair of 75GB SAS drives to host ESX, and 6 300GB SAS drives in a RAID10 array for the VMs.

Earlier this year, I'm looking at a Terminal Services server, a SQL2000 server and an Exchange server that are out of warranty and ned to be replaced. I/O is not an issue with my user base so I went ahead and purchased another server for ESX. This one has a similar disk config, 12GB RAM and a pair of E5440 Quad core Xeons.

Next year's budget has the money for a 2 TB SAN and VC. I'm looking at building my DR plan around backing up the complete VMs. I figure, recovery should be as simple as getting to my DR site, loading ESX, and restoring the VMs. Piece of cake right? ESX shields the VM from the actual hardware, right?

Well, yesterday I was bored watching my server apply patches and rebooting, so I decided to download the 60 day trial of VC. By the time it expires, It will be 2009, with a brand new shinning budget. I loaded VC and started to play with it. First thing I did was try to VMotion a VM. Well, that went over like a lead baloon. Mismatch in register ecx, SSE4.1 error.

So that has me thinking now. What are the odds that my DR company will have the same processors in their server that I have? slim I think.

So our VMs are not quite as portable as we thought. That was a sobering wake up.

How do you guys handle that situation?

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Rockapot
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If you power the VM's down and they are then started in your DR companies VI3 infrastrucutre it would not matter. They would not experience issues.

Roughly speaking the exact processor specification is really only important in your situation with VMotion to other ESX hosts.

The VM's are extremely portable., You could literally place them in any VI3 infrastructure and they would start up fine.

Carl

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Rockapot
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If you power the VM's down and they are then started in your DR companies VI3 infrastrucutre it would not matter. They would not experience issues.

Roughly speaking the exact processor specification is really only important in your situation with VMotion to other ESX hosts.

The VM's are extremely portable., You could literally place them in any VI3 infrastructure and they would start up fine.

Carl

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NTurnbull
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Hi, a good place to start is VMotion and CPU compatibility Info guide. It outlines EVC (Enhanced VMotion Compatibility) functionality which allows for greater CPU family comatibility.

EDIT:

Oh and this error is a VMotion error (hot-migration) and so wouldn't apply if your BC/DR plan is to incorporate system down time while you restore the VM's on the secondary site which is akin to a cold migration.

/EDIT

Thanks,

Neil

Thanks, Neil
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Rockapot
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Neil's link is good.

I am asuming that you have no capability to VMotion to your remote data centre. Are you just replicating the VM's tot he DR site?

I take it that in a DR situation you are planning on just starting all the replicated VM's in your DR site, yes?

If this is the case then there is no VMotion requirement at all so no requirement to really worry about CPU id compatibility.. ( other than just checking for interests sake Smiley Happy )

Carl

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weinstein5
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The cpu compatability requirements are much tighter for vmotion as the others have pointed. in regards to your DR plan it will work as long as you have esx loaded at your DR site you will be able to start up your VMs -

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TiJa
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VMotion is a "hot migration" and requires some aspects of the hardware that is not virtualized away, to be similar in order to operate properly. I don't even want to know how a VM will react when hot migrating it from an Intel processor to an AMD processor :).

In your typical DR situation, you are not hot migrating but rather cold migrating your VM's. This means that the virtual machine is turned off (either by a hardware/site failure or because you decided to do that) and turned on at another location, on another physical box. In that situation, the machine is booted simply on other physical hardware and besides some changes in CPU features that your virtual machines can in fact detect, your machines should start up completely normal as they see they will have the same virtualized NIC's, CD-ROM's, harddisks & controllers, ... (which are typically the hard devices to handle when doing a bare metal restore on different hardware in a physical situation).

Texiwill
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Hello,

VMotion/SVMotion will work for BC but is not really a DR tool. Utlimately DR is starting from VM backups or as with HA, booting from scratch so CPU compatibility is not an issue.

For VMotion to work you need to either employ EVC, which requires the Intel VT and NX/XD be enabled in the system BIOS. If your systems do not have this or you are moving between AMD and Intel systems then you will need to set the per VM CPU Mask. However CPU Masks will not work for 64 bit VMs.

Your VMs are most likely highly portable, however VMotion has its issues regarding CPU compatibility. As a BC tool VMotion/SVMotion is very important.


Best regards,

Edward L. Haletky

VMware Communities User Moderator

====

Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.

SearchVMware Blog: http://itknowledgeexchange.techtarget.com/virtualization-pro/

Blue Gears Blogs - http://www.itworld.com/ and http://www.networkworld.com/community/haletky

As well as the Virtualization Wiki at http://www.astroarch.com/wiki/index.php/Virtualization

--
Edward L. Haletky
vExpert XIV: 2009-2023,
VMTN Community Moderator
vSphere Upgrade Saga: https://www.astroarch.com/blogs
GitHub Repo: https://github.com/Texiwill
Asher_N
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True enough.

For a complete DR, when moving offsite, it's fine that a restored VM will work. I'm looking into EVC, for smaller issues like loosing a host.

And yes, I know, I need to RTFM more...B-)

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