Storage Migrate from vSAN to SAN

[andvm]

Hi,

Why does a VM that is currently consuming 16TB on vSAN (using default vSAN Storage Policy) is unable to be storage migrated to fiber channel SAN Storage datastore of 10TB due to insufficient disk space?

Actual consumption on the SAN datastore will be approx 8TB, is this something that can be listed as an improvement?

Are there any workarounds without having to expanding the SAN datastore to +16TB? (As cannot reduce its size after)

Cannot even storage migrate per disk as largest one is 7TB (14TB used on vSAN). Even if I could I do not think it is a good idea to have a disk on vSAN and another on SAN even temporary (different performance) - would like to see any thoughts on this one ?

Changing vSAN storage policy (to a single copy) could also be another option but there is a higher data loss risk associated with it.

Would like to get your thoughts and suggestions on this one please.

[depping]

Which version are you running? And do you mean 16TB including replica copies or just 16 TB from a guest perspective? Also, is it staying thin while moving?

[andvm]

its a mixed Cluster as I am upgrading from 6.7U2 to 7.0U2

16TB consumed space on vSAN as includes the replica copy

Yes it is staying thin on the FC SAN datastore

[depping]

I have seen something with older versions of vSAN like this, but I am not sure if that was 6.7 U2, let me see if I can find the bug I filed.

[andvm]

from what I see this still applies for 7.0U2 (As I have simulated something similar on another cluster which has all Hosts updated 7.0U2 and still got same error)

If you can double check and let me know please.

[PiotrBerent]

I can only say that the issue still exist on 7.0.3i - build 20842708.

When I'm trying to migrate out VM that have 10TB disks (with thin provisioning and with policy for vSAN that "utilize" 4x space - site mirroring stretched cluster + FTT 1 - RAID-1 (Mirroring)), so if on the VM on all disk total used space is 5TB - on vSAN it reflect to 20TB used space - because of that policy). 

So now when I'm trying to move that VM to LUN on SAN datastore with 15TB capacity - migration will not even start since it shows that 15TB is less than required, and it need to be 20TB+ LUN on SAN.

However, after migration - VM will utilize 5TB (while keeping thin provisioning).

So - is there any other solution to avoid that problem than change VM policy to not redundancy at all?