Soul of a new standard server

IW: Why did you choose Serial Attached SCSI drives over SATA?

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AB: There's a big difference between SAS and SATA in terms of cost performance and market position and so on between the 3.5-inch technology and the 2.5-inch. On 3.5-inch, SATA is now up to capacity points of 500GB, which is substantially higher than the SAS or SCSI drives. [SATA] runs at 7,200 rpm, and they have enterprise-quality drives that are pushing a million hours MTBF [mean time between failures]. Basically, on the 3.5-inch side, there is a whole new category of disks now known as enterprise-class SATA that have a very, very appealing size and performance per dollar.

Going back to 2.5-inch, the only SATA disks available in the 2.5-inch form factor run at 5,400 rpm, and they're basically mobile disk drives. They were never designed for an enterprise class environment. The controller we have can support SATA from a protocol standpoint, but the capacity today is limited to about 120GB and the performance compared to the SAS drives is just not very good. As a result, we didn't see any customer interest in 2.5-inch SATA, even though we see lots of interest in 3.5-inch SATA.

The SFF [Small Form Factor] SAS disks are currently running at 10,000 rpm, but they actually deliver better performance than conventional 3.5-inch disks at 10,000 rpm. Sometime next year these drives will go up to 15,000 rpm, at which point they'll be the fastest disks on the planet, because on the 2.5-inch disk the arm doesn't have to move as far as on the 3.5-inch disk. They come in 36GB and 73GB capacity points today, and they will expand going forward.

But the real reason we picked these SFF-SAS disks is that this allowed us to move the disk drives out of the airflow of the CPU. The entire left section of the box is a perf pattern that's open for airflow so that the air goes through to cool these hot CPUs. As the industry moves from single-core to dual-core to quad-core, the power is not exactly going down. The power density -- which is how much power these multi-core chips will take -- will actually go up even though the power efficiency, which is how much throughput per power you get, is doubling every time you add more cores.

IW: Is the Galaxy's Opteron CPU still a 95 watt part?

AB: No, the new parts are actually 120 watts. The box is designed to handle even higher power in the future as those chips come out. But this is a new thing that AMD did for us -- increasing the power -- because we felt strongly that faster is better. We did all the math based on power consumption and the cost of electricity in California and all that, but what it comes down to is that if you can go 10 percent faster by having a faster chip, as a result you need 10 percent fewer systems to have the same throughput. Under any math, you're better off doing that than using more systems with all the memory and disks and operational costs and running slower. The reason there has always been a premium on high-power CPUs is that the value of that speed to the customer of not having to purchase more software licenses or more systems or using more rack space is very significant.

IW: Do you see this stage of AMD's technology as competent to handle heavy virtualization?

AB: We have to talk about the exact software here. VMware has mastered the art of virtualization, so their software works perfectly well on the AMD Opteron and you can run Windows, Linux, Solaris on top; it all works just beautiful. The open source effort called Xen is in early stages. The Xen effort will be helped by a future hardware enhancement that AMD and Intel will be putting into CPUs coming out in the next calendar year. [Intel VT and AMD Pacifica virtualization technology] will make it easier for the Xen effort to offer the same kind of capability as VMware software today.