I spotted a question this week on VMTN, the question was fairly basic, are nested fault domains supported on a 2-node vSAN Stretched Cluster? It sounds basic, but unfortunately, it is not documented anywhere, probably because stretched 2-node configurations are not very common. For those who don’t know, with a nested fault domain on a two-node cluster you basically provide an additional layer of resiliency by replicating an object within a host as well. A VM Storage Policy for a configuration like that will look as follows.
This however does mean that you would need to have a minimum of 3 fault domains within your host as well if you want to, this means that you will need to have a minimum of 3 disk groups in each of the two hosts as well. Or better said, when you configure Host Mirroring and then select the second option failures to tolerate the following list will show you the number of disk groups per host you need at a minimum:
- Host Mirroring – 2 Node Cluster
- No Data Redundancy – 1 disk group
- 1 Failure – RAID1 – 3 disk groups
- 1 Failure – RAID5 – 4 disk groups
- 2 Failures – RAID1 – 5 disk groups
- 2 Failures – RAID6 – 6 disk groups
- 3 Failures – RAID1 – 7 disk groups
If you look at the list, you can imagine that if you need additional resiliency it will definitely come at a cost. But anyway, back to the question, is it supported when your 2-node configuration happens to be stretched across locations, and the answer is yes, VMware supports this.
Yes, here we go again, the VMUG Advantage Homelab Group Buy Discount offer is available again! I’ve had multiple folks asking throughout the year if I had a code, and unfortunately I don’t have codes to distribute, but I do know that if you fill out this survey, you will get access to a code. The minimum discount you get is 12% and this can go up to 15% when the number of participant goes above 300. What do you get when you sign up and buy a 12 months subscription?