The challenge for ARM servers, at least here
Every so often I think about the theoretical future coming of ARM-based servers (which various people have prophesied for years). Since hardware is on my mind lately anyways, one of the things I've been mulling over is what it would take to get us interested in such a server.
On the one hand, in theory a Linux-based ARM server ought to be easy to integrate into our environment. Assuming that it was supported by, say, Ubuntu, Linux is Linux and we almost entirely use Ubuntu packages instead of compiling our own programs. Adding a different architecture always causes a certain amount of heartburn and annoyance but it wouldn't be a particularly big problem overall.
On the other hand, well, why would we go to ARM over x86? We're not particularly limited by space, power, or cooling in our current machine room so simply being smaller and cooler is nowhere near enough. I think that ARM would have to offer us would be cost-competitive performance in some way in a form factor that was easy to fit into our current rack infrastructure. Actually being merely cost competitive is not enough; since running another architecture does add complexity, ARM servers would have to be better somehow (probably by being cheaper for the same performance).
One way to do this would be to sell us lower-performing servers for cheaper than anyone is currently doing with x86 1U servers. There are a lot of jobs where we are currently using five or ten year old machines. We would be quite interested in reliable $500 servers that could take over those jobs, regardless of what architecture they used. On the other hand I'm not sure that this is really possible due to fixed costs and general overheads in the server market (ARM CPU or otherwise, you still need the sheet metal and so on).
Similarly we're not interested in high-density blade designs. The problem with blade designs is more or less the big hardware problem: unless the chassis is somehow completely dumb you have an expensive single point of failure. Blade designs make sense if you're space constrained, but we're not.
(One of the things that this makes me believe is that the current rack sizes are now too big for small servers. Between 2.5" disks and ARM CPUs and so on you can probably get a decent basic server into a half-width, half depth 1U rack slot, especially if you had some sort of standard rack DC PDU. Expansion slots probably get problematic at that size but most of our 1U servers don't use any. Just make sure that you have a bunch of 1GB or 10GB-T Ethernet ports and you're pretty much done.)