vSAN Storage Policy

[foxdeluxx1988]

I need to expand my 2 Node Vsan Cluster 1+1+1 to 4 Node Vsan Stretched 2+2+1 (2 VSAN Hosts per Site+Witness on the 3rd Site)

the requiremt would be a whole site failure, I have a preferred site and a secondary site with 2 VSAN hosts each. So if the preferred site with 2 hosts fails, the secondary site should survive and take over the VMs from the preferred site. Which would effectively equate to 2 host errors. I have already added the 2 new hosts into the sites. 

In this case, what is the difference between the vSAN Standard Policy for 2 Node Cluster to a new created Policy with 
"Site Mirrored Stretched Cluster-no redundancy" ?

in the document to Stretched Clusters there is only dual site mirroring listed and explained, in my cluster there is only site mirroring available, i think because of the fact that i dont have 3+3+1 for that right?

 

I hope I was able to explain what I mean well, if not please let me know

Thanks 
BR Alberto

[Duncan Epping]

That is correct indeed, you need 3 hosts per location for  redundancy within a location, but you can indeed mirror across sites with 2+2 just like you are doing with 1+1.

[TheBobkin]

Hi Alberto,

There is no difference in the data redundancy achievable in a 1+1+1 vs 2+2+1 cluster - both are going to be storing data as max PFTT=1,SFFT=0 as this is all they can be compliant with (unless have 3 DGs per node and using nested FDs), even if you just use 'Default vSAN Storage Policy' (with unchanged settings) on a stretched cluster it will place data as replica on site A + replica on site B + witness component on Witness.

 

So no, there should be no difference in component placement nor structure when changing between the 2 policies you mentioned, but that being said, it is good practice to change objects for specific clusters off of 'Default vSAN Storage Policy' especially when managing multiple clusters in the same vSphere environment.