Stretched on the rack

Steve Cassidy Read more October 7, 2009

There is a whole arcane, hidden world out there, sitting just out of sight of most small network builders and users. It is the world of rack-mount equipment – the art of wedging your kit into a steel cage so it lives together in one place. Cabinets are all 19in wide, and so is what goes in them: even the march of metrication cannot penetrate the imperial preserve of the equipment rack. The business logic of the web pushes data centres into squeezing as many servers as possible into a tiny space, and so the whole server sector has trained itself to speak rack first and open-plan offices as only a poor second. The server vendors imagined that the whole business world was gagging to spend oodles of cash on web-enabling themselves, and that all the old kit wobbling about behind the photocopier would quickly be rearranged into a tidy rack.

Hence, you can buy rack servers from just about anywhere nowadays, but the floor-standing equivalents are much rarer and more likely to be on ‘back order’ (that kiss of death for so many speedy upgrade projects). This state of affairs has led to a number of my clients’ operations investing heavily in first some rack-ready servers and then pretty sharpish some racks to put them in once they discover that the ‘rack’ in ‘rack server’ is not short for ‘rack mount’ so much as for ‘racket’. A modern rack-mount server is basically a large rectangular conduit for air, with a few chips and other components placed so as to partially obstruct its flow.

When designing for web data centres, the server vendors took account of the fact that web hosts charge by the amount of data you move and the amount of space you take up in the cabinet – in the jargon, how many Us you take up. They also took account of the security measures common to large web centres: the servers are left behind lock-and-key in unmanned spaces, and therefore can be allowed to make as much noise as they want. This simple fact produces a short and highly frustrating chain of consequences for small businesses. They buy a rack-mount server, set it up in the office, realise they can no longer hear the phones ringing once it is turned on, rush out and buy a rack to put it in and then discover that a locked-up rack-mount server responds to the confined space by increasing the speed of its fans, which shifts more heat and makes yet more noise. The whole adventure soon starts to resemble a session on a rack of the medieval kind.

Rack-mounted kit likes to be cosseted. More often than not, it is designed to live in an air-conditioned room and, while equipment catalogues will show you slinky pictures of racks with glass doors on the front, there is a damned good reason why the racks sold by the big server makers come instead with perforated steel grilles where everyone else puts glass. They know that the priority is to suck in cold at the front and throw out heat at the back.

Many people I talk to are at a loss to understand how some larger companies can spend hundreds of thousands of pounds on a PC server. Anyone who has foolishly bought a rack-mount version of what they needed (because they were in a hurry or misread the catalogue) will be aware of the steep climb in costs that leads smoothly from that base price of circa £1,500 all the way up to £20,000 and beyond.

A case in point were some clients of mine who took up my suggestion to purchase a nice lockable Compaq-specific cabinet on eBay, just a shade under 6ft tall with the keys still present. Given that they have a pile of Compaq servers, this seemed ideal, except that at that size there was no way each server could simply be slid in, attached at the front by rack-bolts and left in place. Each one would need its own set of rails fastened at the back and front, or else a shelf on which to sit. Given the mishmash of cabinets and desks in their computer room, these clients had long since reorganised, mislaid or simply never ordered the matching rack rails for the servers currently in active service, so they ordered some shelves on which to stack the servers. A new set of three of the correct-sized shelves to fit the official Compaq rack totted up to 150 per cent of the price paid to the eBay seller for the whole rack.
Motivated by this realisation, we looked in the various catalogues for the list prices of the various racks, rails, cabling bridges (those things that hold the cables neatly while you slide the server in and out on its rails) and other sundry bits of bent steel considered vital when playing rack meccano. The total cost of all the parts we would accumulated by various means, as bundles with servers and by purchasing on eBay, came to a tad under £4,000. Paying peanuts for this stuff second-hand is one solution, but it brings hefty shocks when you find you have to add a part at full retail price to the overall deal.

Having said all this, the end result of a well-setup rack installation is worth having. All your equipment in a movable unit on wheels with enough room to get round the front or back, a couple of cleanly identifiable mains power feeds and a nicely arranged bundle of network leads going into a well-organised cable tray (£250 each, fits only one brand of cabinet, made out of old yoghurt pots). This is inherently very appealing – not perhaps four grand’s worth of appeal, but still a good idea.