Unable to convert 10GB hard thick disk to thin disk

[JohnVMware123]

I've done storage migration a week ago to convert thin(10GB hard disk) and it was successful at that time and I saw it was converted to thin. After couple of days, It was automatically converted back to thick. and It happened couple of times already, tried on few other VMs too which are having 10GB, same thing happening, After few days converting back to thick.  I was wondering if there is any disk requirements to do storage migration? anyone have any idea? I've done large disks over 50GB, they are fine. Just having trouble with low size disks

-Thanks,

Rahul

[DavoudTeimouri]

You can use traditional backup solution for converting thick disk to thin disk.

Clone the current disk by Acronis or other tools to a thin disk.

[tomtom901]

@David: Totally unrelated to the problem. A storage vMotion should easily be capable of performing this task as the TS mentions.

@TS: Perhaps there is some automatic task running on the VM to convert it back, I don't see the relevance with the smaller disks here. Check the events tab (Under Tasks & Events in vCenter) to see what has been running on the VM. That might give you some pointers.

[rachelsg]

Hi

Here are some limitations. Are you gone through this.

Hope you have followed below kb.

Reload the .vmx file. For more information see Reloading a vmx file without removing the virtual machine from inventory (1026043).

[JohnVMware123]

Thank you for your reply Tom. I don't see any newer events running by VM, All I can see only storage vmotion in the tasks which I have done. It's so weird that I've converted to thin 3 times then it converted back to thick itself. Any other ideas?

Thanks

[tomtom901]

Right after the conversion, does it say thin?

[continuum]

Maybe the vmdks are so busy/full that they are defacto thick disks - no matter if they are flagged as Thin.
To verify that run vmkfstools -t0 against the vmdk in question.
If there is not a single line containing the term NOMP the vmdk is thick - even when the descriptor.vmdk still says
ddb.thinProvisioned = "1"

[JohnVMware123]

Tom, Yes it says thin for a day or 2 then converted back to thick again

[tomtom901]

I'm curious to see what the outcome of the post from continuum is. Did not know this. Otherwise, we'll keep on going.

[JohnVMware123]

Actually these 10G disks are not full and they allocated these for logs. They are almost empty just used 10% out of it

[tomtom901]

John,

Which build of ESXi are you running, from the commandline, do:

~ # vmware -v

VMware ESXi 5.5.0 build-1331820

[JohnVMware123]

5.0.0,1024429

[JohnVMware123]

Do you think it's a bug in that build?

[tomtom901 · Accepted solution]

John,

When you do the storage vMotion, did you select a different datastore then the one the VM was on? If not, try that one.

[JohnVMware123]

I've selected different data store only

[tomtom901]

How do you mean, did that fix your issue?