I have a DS920+ full of 16TB HHDs. I am considering adding a DX517. Is it possible to move my HDDs into the expansion unit and maintain the existing raid while installing SSDs into the original four bays? Does it make sense to put the HDDs in the expansion because they connect over a single eSATA cable? Does it make any sense to try and optimize like that considering all of the NICs are 1gb?
I’ve never done it but it is my understanding that you can move the drives around. The expansion unit literally just makes it seem like you have more slots in your existing system. The system identifies the drives by their UUIDs which is why I’m thinking it isn’t a crazy idea to be able to move them around.
I had a nas server with a raid card where I had to ensure a specific drive went to a specific sas port but I think this is more like ZFS where you (and in this case DSM automatically) can just identify drives by their ID.
I like the idea of a second unit but in my case the newer models don’t seem to use intel anymore and don’t have h.265 decoding offload. If that isn’t important to you or you’d buy an older model then maybe not a terrible way to go.
Finally, I don’t know your comfort level but building a little NAS server from older gen server/workstation parts off of ebay (minus the drives) will get you pretty far bang-for-your-buck wise.