Ensuring that two vSAN disks (FTT=0) do not hit the same node/disk

[jancipra]

Hi,

I have a situation that we need to provision two virtual disks (on vSAN datastore) for a VM, the disks will form an software RAID 1 in the VM (that is requirement of the application). So if I will provision the disks with FTT=1, I will have 4 copies of the data which is wasting of capacity. On the other hand, If I will provision the disks with FTT=0, I will be in risk that the disks will hit the same node/disk and make a SPOF.

Is there some hidden parameter that will ensure that the two disks will be stored on different nodes in the vSAN cluster?

Thank you for answer.

Jan

[Daisukey1380]

Hello,

If we use RVC or clicking the Rebalance Disks button on vCenter server, we might be able to move components randomly.

Manual Rebalance

But I could not find the operation that can move specific component to specific disk/host.

Regards

yammy

[TheBobkin]

Hello Jan,

Unfortunately there is no current way of achieving storage affinity/anti-affinity of Objects (other than in Stretched-clusters and using site-affinity but that still won't let you pick the host/disk). If I recall correctly it was raised as feature request at some point but I am unaware of whether this will be implemented nor when.

Edit: actually pinning FTT=0 Objects to nodes was introduced in 6.7 but is only available via RPQ so consider talking to your VMware account manager for more information if you want to go this route.

Bob

[daphnissov]

I would approach this from another angle. No application which is virtualization-ready should be specifying in-guest RAID like this. It's a horrible idea and provides nothing. It sounds like this requirement is a hold-over from the physical days. I would go to the team responsible and get clarification on the requirement, because it makes zero sense when virtualized.