HCI - Storage Spaces Direct - Two nodes

Well, quite a lengthy answer, I’ll try to answer some of the points you brought up.

Beancounters are an important factor to take into consideration, too. As long as you can afford to get the redundant storage, you should be fine. However, unless a single node can sustain the entire load of all the VMs you won’t be able to do things like patching during production hours. Reading your message a second time, I noticed you covered this. :)

I was thinking on installing at least one local (not clustered) DC as a VM on one of the nodes (possibly two, as I have four in total). Unless you have another DC beyond those two, it will be a lengthy and major pain to restore in case you have an AD outage. Try to keep at least a DC VM as a single DC, and nothing else (and DNS, of course). If you have so many roles, it’ll take a lot of time to restore and clean-up everything.

I am not a storage expert, but backup on disk is definitely faster and less painful. I don’t know about agents for specific apps (which may provide faster and more granular restore options for a database or CRM or whatever), but at least for Windows infrastructure Windows Server backup is good and reliable. Since it no longer works on tape, a bunch of disks would be great (I plan to use the old storage for that).  However, if you plan to ditch the tapes, make sure you’re using a more sophisticated file-system (that can handle bit rot, for instance). If you still have some tape library laying around, you could still do a less often backup for things that really matter.

Moving on to Kepler. It’s not my project, so I cannot not give you more number than what I’ve read in the post.

As I’ve struggled a lot with S2D (I’m not a storage guy, and not a great networking guy, either), this step-by-step article for 2-nodes HCI helped me a lot to clarify some fuzzy concepts.

https://www.tech-coffee.net/2-node-hyperconverged-cluster-with-windows-server-2016/

And now for some more performance-related links. As some of them are from vendors, they may be useful but take them with the proverbial grain of salt:

https://docs.microsoft.com/en-us/windows-server/storage/storage-spaces/performance-history

https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/subsystem/storage-spaces-direct/

https://www.micron.com/about/blogs/2017/september/microsoft-storage-spaces-direct-is-an-io-performance-beast

Also, https://youtu.be/raeUiNtMk0E?t=274 for some numbers.

There was another post from a Microsoft PFE, in which I remember the last picture of the post was a screenshot showing 1GBps copy between nodes, but I couldn’t find the link.

I hope you found at least some of these bits helpful.

Cheers. Emanuel