Today I came across an issue I did not immediately think about selecting a data protection or replication solution for a vSAN deployment:
Let us say we have a vSAN datastore as target for a replication (failover target) or a data restore from backup. But what if your data protection or disaster recovery/replication product does not support storage policies?
You might find yourself facing some unexpected problems.
The restore or failover might succeed but your VM files (including VMDKs) are subsequently protected with the vSAN default policy. If you did not modify it, this will result in FTT=1 and FTM=RAID1 (If you are not familiar with FTT and FTM, search for in conjunction with vSAN).
At first glance, this does not look too bad, does it?
Now what if the source VM was protected with FTT=2 and FTM=RAID6?
The restored VM has now less protection with more space consumption and the VM might not even fit on the datastore, even if the clusters are setup identically or even it is the same cluster (in case of a restore).
A VM with a 100GB disk is consuming 150GB at the source vSAN datastore (with FTT=2 and FTM=RAID6 ) and is able to withstand two host failures. However, it would consume 200GB at the destination datastore (with FTT=1 and FTM=RAID1) as the latter would create two full copies and only one host failure can be mitigated.
Sure you could modify the default policy for this, but what if you have different settings? The beauty of SPBM lies in the fact that you can apply it per disk and re-applying the policy settings for a more complex setup will become messy and error prone.
Now if you ask me for a good example on how to do it:
Veeam shows how to integrate this here.
VMware offers a storage policy mapping in SRM