most folks wrote off the SGI brand as an historical remnant.The "G" in its name used to stand for "Graphics." A few decades ago, the most delightful room for one to be in during a computer conference was the one where Silicon Graphics was showing a demo. It was like one of those dreams where you knew you weren't really on-board the Starship Enterprise, but you forced yourself to ignore that fact and look at the pretty lights and colors. When SGI ceased to be a company unto itself in April 2009,
Wrong. It's wonderful to see a brand that never says die. Ever since Rackable Systems adopted the SGI name, it's been lucky. It's finding its way back as a high-density storage provider. This afternoon, the company is introducing a very high density storage server platform designed, its engineers tell us, to pack the maximum number of terabytes into a 19-inch rack while staying cool.
The result is what SGI describes as a module full of "drive bricks." Each brick can be loaded with up to nine 3.5-inch SATA or SAS drives, or 18 2.5-inch SAS or solid-state drives. If you've ever washed dishes in a cafeteria, you may have experienced something similar to the situation of hot-swapping drives in a storage rack. So SGI used a little something called "computer-aided design" to engineer a solution.
"Any time you get a system that is this dense, data center managers need to be able to access it," SGI's director of storage products, Floyd Christofferson, tells RWW in an interview. "If you've ever pulled out a large, very dense system, typically they only allow access from the front. The weight of those trays pulling all the way out adds a lot of strain on the internal cables. In large data centers, people would like to be able to access these hot-swappable parts, but really don't want to do so in a way that either puts strain on the rack itself or on the internal components."
So the slider on SGI's Modular InfiniteStorage (MIS) units can be pulled from the back or front on a nice drawer, all without tripping up a cable or maybe tripping off the power.
Each 4U MIS chassis may have one of two configurations. One is as a storage server with one or two motherboards, each with dual-socket Intel Xeon E5-2600 "Sandy Bridge" processors clocked at up to 3.3 GHz. The remaining space can be populated with either 72 3.5-inch or 144 2.5-inch drives. Alternately, the unit can be maxed out with 81 3.5-inch or 162 2.5-inch drives.
So with that many drives packed that close together, how do they keep from becoming a virtual radiator unit? We asked SGI's chief storage architect Lance Evans, who told us there's a secret in being tight but not too tight. When you push air into certain spaces under pressure, it's like breathing in through your mouth with your teeth shut tight.
"Imagine a cross-sectional slice through the chassis. At any given point along the front-to-back axis of the chassis is a certain cross-sectional air channel," explains Evans. "The smaller those channels are, the higher the pressure that the air channeling system has to be able to generate to pull more air through. Second, you have to be very careful about where that air flows. It needs to be able to flow over the components that are generating heat. If we have airflow through the machine, but it's not passing over components that are creating heat, then it's really not doing us much good. Every last little bit of air that you pull in, you need to be able to use effectively to cool the machine."
So SGI designed a high-pressure air movement system, comprised of six 60mm twin-axial, high-RPM fans positioned in the middle. They're stationed in such a way that, if one of the fans fails, it doesn't result in backflow.
Doing some math on the fly, Evans estimated the total power requirements for a fully populated SGI MIS rack at about 20 kW. That's on the high side of normal, compared to recent analysts' estimates, and perhaps a bit above normal for rack requirements circa 2009. But with firms like Dell now warning customers to expect as much as 30 kW per rack, MIS may be a viable solution for fitting big clouds into tight spaces.