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 Storage vMotion from large datastore to smaller datastore

Jacky Chan's profile image
Jacky Chan posted May 09, 2024 04:06 AM

Hi, I'm using vSphere 7 and I have a VM using thick provisioned VMFS 6 shared datastore that is 500GB in size (i.e. VMDK is 500GB). The actual OS usage is 100GB only. Due to some reason, I have to move the data to a VMFS 5 local datastore that is only 200GB in size. The VMFS 5 local datastore is created but I don't see any VMs are using it, so it can be recreated if needed.

Under this situation, do I need to first remove the VMFS 5 local datastore and create a 200GB VMFS 6 local datastore. And then use storage vMotion, choose the 200GB local datastore, choose thin provision to migrate the data? 

Jacky Chan's profile image
Jacky Chan

Hi, would anyone be able to help with this question?

Franky Barragan's profile image
Broadcom Employee Franky Barragan

I'd do exactly what you're saying. Since nothing is on the v5 datastore, I'd tear it down and create a VMFS 6 datastore then svMotion the VM with Thin provisioning. 

To tear it down, you'll have to put that datastore into maintenance mode. That will tell you if it's truly empty.  

Jacky Chan's profile image
Jacky Chan

Hi Franky, the original VMDK size is 500GB, but the new VMFS 6 local datastore is 200GB. Can storage vmotion reduce the datastore size to the actual usage 100GB by selecting thin provision? I tried the storage vmotion and chose the VMFS5 local datastore (I haven't re-created this yet), but there is error message that the destination datastore doesn't have enough space (even I have chosen thin provision) and not allowing me to move forward.

Franky Barragan's profile image
Broadcom Employee Franky Barragan

Shoot. A storage vMotion won’t reduce the size of the datastore. Since you’re getting that error, try the vCenter Converter. I’ve used it in the past to clone (V2V) the VM and shrink the disk that way. 


Im on my phone, but can try and look for a download link tomorrow. I can walk you through the process as well. 

Jacky Chan's profile image
Jacky Chan

Thanks for the feedback. How about clone the VM/datastore to another datastore that has enough space with thin provision first. And then use storage vmotion to the local disk which is smaller in size? 

Franky Barragan's profile image
Broadcom Employee Franky Barragan

The converter will “clone” the VM and you’ll have the option to shrink the VM disk and place the VM on that smaller datastore at the same time. If you just clone the VM through vSphere, the disk size will stay the same. 

Franky Barragan's profile image
Broadcom Employee Franky Barragan

Here is the link to the Standalone vCenter Converter - https://support.broadcom.com/group/ecx/productfiles?subFamily=VMware%20vCenter%20converter&displayGroup=Standard&release=6.6.0&os=&servicePk=203348&language=EN

Jacky Chan's profile image
Jacky Chan

Thanks Franky for all the information. I will do the conversion in the next few weeks and update you after that.

Jacky Chan's profile image
Jacky Chan

HI Franky, the solution works well!