Tuesday, December 14, 2010

sVmotion fails with (vim.fault.InvalidDeviceBacking)

Wow, it has been crazy over here these last weeks…
I’m working on the upgrade of my environment from ESX 3.5 to vSphere 4.1, including some scripted installation of ESX, new templates, etc…
probably the new posts will be about migration ; )

For this one I selected an issue that was really bothering me for some time.
When I tried to perform a storage v-motion (sVmotion) a few guest hang with “A general system error occurred: failed to copy VM config to VMotion dest (vim.fault.InvalidDeviceBacking)”

First I wanted to make sure the problem was not with my environment, so I tried another sV-motion for another guest, on the same host with the same source LUN and going to the same LUN. This time it worked fine.

Another curious fact is when I try to see the disk information on the guest’s properties page the disk size is unavailable and the virtual disk become high-lighted, just like if I did some change.

So my conclusion was that the issue was with the guest !!

After several troubleshoots and attempts I figured out that the vmdk files were configured with full path on the vmx instead of the relative one.

Something just like that:

scsi0:0.name = "/vmfs/volumes/45d0b927-82211d90-ba07-000e0c830b29/guestA.vmdk"
scsi0:0.fileName = "/vmfs/volumes/45d0b927-82211d90-ba07-000e0c830b29/guestA.vmdk"

So I decide to remove the disk a re-attach them back.

After I removed the disks from the guest I took a look at my vmx file and realized that entries were not updated to reflect there’s no more disks on the guest.
So, I manually delete those lines.

Then I add re-attached the disk back through the VC, and the vmx reflected the change with the relative path instead the full path,

scsi0:0.fileName = "guestA.vmdk"

If you realize the entry scsi0:0.Name was not created anymore.

Since the guest is running fine and sV-motion back to work again I was wondering how it went in there ?!?

My though is that it’s an old vmx entry for older version of ESX…. Since I have an old environment, backing to ESX 2.0, that has been upgrading since them… some guest can be that old and have had several upgrades and in some cases inherited some old setting.

Some of those cases I saw a header in the vmx like:

### Created by VMware ESX Server 2.0.0 Config Wizard (05/08/07)

That’s all , hope it helps you..

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I’m and IT specialist with over 15 years of experience, working from IT infraestructure to management products, troubleshooting and project management skills from medium to large environments. Nowadays I'm working for VMware as a Senior Consultant, helping customers to embrace the Cloud Era and make them succefully on this journay. Despite the fact I'm a VMware employee these postings reflect my own opnion and do not represents VMware's position, strategies or opinios.

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