vsan space n+1?

[gbrown2]

I just set up a 3 mode cluster with VSAN. Each node has 7x1.2TB HDD and 1x 400GB SSD.

With all setup, I am seeing the VSAN Datastore as 22.92TB, but when I reboot a node for maintenance I see 15TB.

I want to plan for host maintenance and outages so I don't want my team to over provision past the 15TB.  Did I miss a step to say reserve space for maintenance or N+1?

Any help would be appreciated.

-Glenn

[CHogan]

Planning for additional capacity in a 3 node cluster to handle a maintenance mode scenario doesn't really make sense.

You would need at least 4 nodes if you wanted to evacuate the data on one host to the remaining hosts in the cluster, and maintain a failures-to-tolerate = 1.

The reason for this is that you need at least 3 nodes for FTT=1.

I would let your team provision across all 3 nodes in this scenario - if you plan to introduce a fourth node at some stage, then it is worth setting that aside for this exact reason.

In fact if you plan to go to 8, 16 or even 32 nodes, and still use FTT=1, having one node worth of capacity is still enough to set aside for this.

If you plan to use FTT=2, consider setting aside 2 nodes, and so on.

HTH

Cormac