Our latest toy.. is a custom built rackmount blade-style server hosting system.
It allows you to put 70 standard servers in a (43U) cabinet.. that’s 560GB of memory.
5 servers per 6U box, mounted back-to-back, with two 48port switches back-to-back.
I know what you are thinking.. 70 is not that much? Sure. If you mounted 1U servers back-to-back you could fit 84 servers (42*2). When I worked for Amazon.com they used to buy cabinets full of servers from Rackable Systems with this design. Nice stuff.
but…. the keyword here is standard. Stock standard, cheap, commodity hardware. Easy to find spares. Easy to support. To put 84 in a cabinet is nice, but it’s very custom stuff.. and usually very expensive.
70 servers is also a bit easier to cool than 84.. well, we will soon find out.