So after reading a ton of Docs and watching a few videos, I'm still very unsure whether we should move to HyperConverged platform.
Currently we have a Hyper-V cluster that spans 2 sites, and it all sits on the old HP LeftHand solutions P4500s. Our VMs can swim around from site to site, and if one site fails everything can live happily in the other until the problem is resolved.
Now it's time to renew the infrastructure, and we're taking the opportunity to re-look at how we do things, and of course management is looking to keep costs down.
So obviously Azure Stack HCI is something that has come up.
My concerns are as follows, and I'm hoping someone will be able to fill in the blanks and correct anything I've got wrong...
With S2D the best fault tolerance you can currently have is 2 nodes. So with a HA cluster stretching 2 sites, the maximum number of nodes you can have is 4 nodes, 2 in each site, because as soon as you move to 6+ nodes and one site fails you will be
over the 2 node limit and the storage will fail. So in this situation 4 nodes is the limit, which would be very tight for us.
We can add in Storage Replica, and use cluster-to-cluster replication. In this case we can have an S2D cluster in Site A, and replicate to another S2D cluster in Site B. However, there's no automatic fail-over, you have to manually bring everything up, and
we can't have that.
You can have Storage Replica with a stretch cluster that does support automatic fail-over, but only with Storage Spaces. Losing all the goodness of S2D.
The best of both worlds would be to have Storage Replica, stretch cluster, and S2D volumes, but this is not supported
Also, there appears to be a big question surrounding log placement for Storage Replica, as it needs to be faster than the data disks. So in effect you can end up limiting the benefit of the cache in S2D, to ensure it's not as fast the volume for the log.
Plus as it starts as a low cost solution, but as soon as you start building it up the costs go up a lot.
I really like the look of S2D, it looks great. I just can't see how it will work for our environment. We're also looking at the HP Nimbles.
Andrew
Andrew France