vSAN Stretched Cluster with 4 nodes. 2 Nodes on each side

[leotaglietti]

Hello, Team.

Is anyone know if it's possible uses vSAN Stretched Cluster with 4 nodes being 2 nodes on each site? I believe that it's not possible or if it's possible there is a necessity to use additional vSAN witnesses on each data site (to be compliant with vSAN RAID1) beyond the vSAN Witness between de data sites.

Regards.

[paudieo]

in your scenario you can use 2 + 2 + 1 for stretch cluster,  meaning you need an additional a witness host which can be a ESXi virtual applance or a physcial host 

You need 3 sites to implement  a witness

That means 2 hosts are part of one Fault Domain on one Site, the other two hosts would need to be on the second site Site

A 3d site then is needed to host the witness appliance

have a read off this guide https://core.vmware.com/resource/vsan-stretched-cluster-guide#section1 

[leotaglietti]

Hello Paudieo. 

You say that is necessary uses additional witness for each fault domain in order to be compliant with RAID1 police? Beyond the vSAN Stretched Cluster Witness in the thrid site?

[paudieo · Accepted solution]

no

its one dedicated witness host per stretch cluster

if you go with 2+2+1 you will be able to implement raid-1 acorss the stretch cluster, but no local redundancy

if you want secondary faiiures to tolerate , which gives you local redundancy as well as site level protection  you need 3 hosts per site

i.e. 3+3 + 1

In all cases you need one witness host per cluster, and  hosted in a 3rd site

its all outlined in the doc I shared

https://core.vmware.com/resource/vsan-stretched-cluster-guide#sec7306-sub2