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I just got a 15" MacBook Pro with 8GB RAM, 2.66 i7 and 500GB SSD. Very sweet and fast! My old machine was 2.66 Core 2 Duo.

I used Migration Assistant to migrate my old MBP to the new. When I started VMware to run Windows and Ubuntu I got the message first This VM has been moved or copied to a new machine. Did you move or copy it? I answered Copied. Then I got the message this CPU is a different configuration than the machine that created the VM. You may get unpredictable results. I answered Open Anyway.

Windows XP, Windows 7, and Ubuntu all seem to work OK, but how can I verify? Is there some form of test harness for a VM? I have had a VM degrade and become unusable with very catastrophic data loss (on Parallels...), so I am a bit paranoid.


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2 Answers

up vote 2 down vote accepted

VMware (and Parallels, come to that) will ask you whether you moved or copied the VM because it needs to know about it's MAC address. Choosing Moved or Copied depends on if you intend to now use 2 VMs or delete the original one and only use it at the new location.

You may have just moved the VM (in your case) to another machine or directory, in which case you'll probably want to keep the same MAC address. If you've copied the VM, for example as Josh K mentioned for a sandbox to test things out, you should tell VMware this and it will generate a new MAC address for the VM.

Some software licensing mechanisms may be tied to specific MAC addresses, so if the MAC address is changed, that software may not work any more.

I don't know of any tests you could do other than perhaps verify the disks (e.g. fsck in Ubuntu) in the guest OS? The cynical side of me would guess that 'you may get unpredictable results' is a just a broad disclaimer meaning 'don't blame us if it goes wrong'!

I second Josh K's comment about keeping backups!

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It is a fascinating thing to me. You can test a computer for function, you can test a file against its CRC, you can test a disc for errors, but I have yet to find a test harness for a VM. With all the VM'ing being done, you would think that there would be one. I did find academic papers on it, but no solution... Thanks for the answer... –  drewk May 16 '10 at 23:23
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Considering Parallels has it's own issues, I would simply keep a backup of the VM.

Most of the time VM's are sandboxes for testing out various things without putting the actual OS at risk. They can be scrapped and reloaded pretty easily. I believe VMWare actually "tunes" the installation to the CPU for better performance, though I could be wrong.

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Since I asked this question, I have upgraded VMware to RC 3.1 which has PHENOMENAL performance in comparison to V 3.0. Perhaps a 50% or great speed increase vs the previous version. No issues so far with the VM's that were moved. Thanks for the answer... –  drewk May 16 '10 at 23:18
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