For me, it depends on the market you are trying to target.

If you really want datacenter-type gear, I'm a big fan of blade systems.  Even from the old days of the IBM HS20/21 blades all the way up to the modern Cisco B-series stuff, it's super convenient.

House all the management and intelligence in the chassis, and all the power/connectivity.

Blades would just be additional hash modules.


Probably not feasible, and I'm sure expensive, so it won't happen.

As for individual rackmount systems, 2U or 3U is fine.  No idea where these 44U racks are, every datacenter I've been in has been 42U racks.  Since systems/network are what I do for a living (as a consultant), I've been in hundreds of datacenters in just the past few years.  Can't recall seeing a single 44U rack, though I've seen plenty of weird 21U floor standing and 11U & 7U wall mount nonsense.  That said, with the exception of SANs (which are all sorts of different sizes) and large core switches, damn near all gear these days is 1U or 2U.

Redundant hot-swap power, and if you're going to have a CRAPLOAD of hash per box, redundant network as well.  It would make me sick to think that I've got 100TH in 3U and a bad NIC took it out.