Serious BUG in VmWare CBT

Ended up seeing some internal VMware info on this.  The problem has been around since 2007.  There is a hotfix for 5.5 if you call support and will be available in an update in Jan 2015.  Apparently working on a hotfix for 5.1.  Was also told that it is it fixed in 6.

Thanks Cogswell, do you by any chance have an ID on that hotfix?

/tony

I do not have it but if you call about this issue specifically they may give it to you.

Anthony

Veeam has a script to help with the issue. 

http://www.veeam.com/kb1940

Basically just finding all the VMs with CBT enabled, flipping the bit and snapping/unsnapping the vm to reset it all.  Only issue is it is going to do all VMs even if they do not have a VMDK over 128GB. 

Really what we need is a script to extract the VMs with at least one VMDK over 128GB and redo those ones.  Even better if it could detect if it was expanded over one of the powers of 2. 

Nice!

Thanks Anthony.

And yes, you're right about the need to extract a list containing just the vm's that might be affected. Hopefully we will get a fix sometime soon.

/tony

This sure doesn't seem to get as much attention as it deserves... Would like to see Avamar / MW put a check in to detect the disk change and reset CBT similar to the one Veeam just implemented.

This post is a bit late, but I only just noticed this thread.

I'm still concerned about the lack of attention to this issue. I note that VMware have quietly released fixes for this issue in ESXi 5.0 UP10 and ESXi 5.1 Update 3. ESXi 5.5 is still exposed, but rumoured to be getting a patch in Jan 2015.

Commvault and Veeam have also supplied patches to automate workarounds. Hopefully Avamar and Networker to follow suit soon.

When this issue first came to light in Nov, I wrote a quick script to assist with mitigation in my own environment; which only touches VM's with Hard Disk sizes greater than 120GB and where CBT is already enabled.

#---------------------------------------------------------------------

  $targetvms=get-vm | where {$_.ExtensionData.Config.ChangeTrackingEnabled -eq $true -AND $_.HardDisks.CapacityGB -gt 120}

$vmspec = New-Object VMware.Vim.VirtualMachineConfigSpec

$vmspec.ChangeTrackingEnabled = $false

foreach($vm in $targetvms){

$vm.ExtensionData.ReconfigVM($vmspec)

$snap=$vm | New-Snapshot -Name 'CBT enable kb2090639'

$snap | Remove-Snapshot -confirm:$false}

#---------------------------------------------------------------------

(this will also take and then remove a snapshot to stun the vm and commit the config change and runs sequentially)

There's lot's of other ways to limit the scope by changing the leading "Get-vm" by leading it from a "get-cluster" or "get-resourcepool" pipeline.

I've included more details on my blog also. (but posting them is tripping up the spam filter !)

Will try and include links in a new post .

Hope this is useful to some of you..