ESXi

I have 5 different disks I want to storage vMotion. The largest is a 4TB disk where 3.5TBs are being used

• ESXi 6.7 Update 3
• Datastores are all VMFS 6
• Underlying storage is a Nimble all flash array, VAAI is enabled
• I plan on doing this storage vMotion with the VM powered down

Any idea how long this will take to vMotion this 4TB disk?

Why are you doing storage vmotion in a virtual machine power off way? You can do it while Virtual machine power is on. I think it is completed in an average of 1 hour. The completion time does not change much if the virtual machine is power on or power off.

I kept thinking that storage vMotion would be faster with the VM powered off

The host and SAN are all connected via 10 gig so it should only take about an hour to migrate this 4TB volume even with the VM running?

During storage vmotion, the amount of I / O to the virtual machine is reduced. Therefore, in case of power off or power on, there is not a big difference in duration during transportation.

If failure is no option and you need a failsafe approach - here is what I do when the vmotion button is out to lunch.

Power off VM.

Remove all snapshots.

Add a snapshot / delta  to the valuable 4 tb vmdk only.

Move the empty - because yet unstarted snapshot to the target directory.

Adjust vmx and vmdks.

Power on the VM - it runs the 4tb vmdk from the snapshot in the target location.

Now you can use vmkfstools -i and clone the base-flat.vmdk to the target location too.

You are in no hurry now.

If something goes completely wrong -  you still have the original basedisk in untouched state ,,,

Then when the clone is done you need another 5 minutes maintenance window to attach the snapshot back to the base.vmdk in the target location.

You can do this for one or for all disks.

For all disks would be slightly easier - creating a single snapshot for one disk only is straightforward but takes some extra steps.

Looks like a pain at first sight - but it is failsafe.

I always use this approach when I prefer predictable results over convenience.

Anyway - you still have full control when this goes wrong - you just wasted time - if the automatic function fails results will be less favourable.

Hi,

I add these links in addition to the answer from "Tayfun DEGER" because you can take some ideas:

How to estimate storage vmotion migration time?

Storage vMotion speed and Throughput

ARomeo