Best practice configuration 4-node cluster with FTT 1

[sschlabs]

Dear community,

i'm dealing with vSAN since a couple of weeks and want to integrate it into our vSphere infrastructure during my trainee final project now. I'm now facing the question mentioned in the title.

We've a cluster with 4-nodes. 2 hosts of them are located in Rack A and the other ones in Rack B. I want to create several fault domains in order to save the objects exclusively on the hosts of each rack where the machine is running. For example: Machine 1 is running on a host in Rack A -> Objects should only be saved on the 2 hosts in this rack.

As far as i'm aware of vSAN i need at least 3 FD's with an additional witness appliance and create some storage policies for the machines.

What would be the best design regarding this topic? Should i create 3 FD's (on of them with 2 hosts)?

Thanks in advance for your support,

Sebastian

[admin]

Hi,

there is something you misunderstood about witness. witness appliance is needed for only stretchered  vSAN cluster. if all hosts resides on same location, you don't need it.

when you create VM with FTT=1, there will be 3 components. data, replica and witness.

in your case, you don't need to configure additional fault domain. each host will be running as implicit fault domain.

if you would like to use "rack awareness", you need to have at least 3 racks for FTT=1

but it wouldn't be much helpful for 2 rack.

[virtualDD]

Hi,

I agree with Byounghee, but when I think about it what you want to achieve is very similar to a streched cluster. even tough you aren't really stretching your cluster.

If you want to make sure a rack failure does not impact your machines and you cannot add any more hosts (like Byounghee suggested with an additional FD) then you could do a streched cluster configuration where hosts in rack A are a FD and hosts in rack B are the other FD. But in that case you would have to use the Witness appliance as a quorum in case of a rack failure preferably on a third site/rack.