IBM Launches Promised 32-Way Intel Server

by Timothy Prickett Morgan

After a long wait that was due primarily to the delays in bringing 64-bit Windows and 64-bit Linux operating systems to market with a suite of suitable applications and 64-bit Intel Xeon processors to match them, IBM has finally delivered on its promise to get a 32-way X86 server to market. Last week, IBM rolled out the xSeries 460, which, like the xSeries 366 announced a few months ago, is based on Intel's new 64-bit processors and IBM's X3 "Hurricane" chipset.

According to Jay Bretzmann, director of eServer products at IBM, the company could have put a 32-way Xeon server in the field with its "Summit-II" EXA chipset. But with Intel running late with its "Potomac" and "Cranford" 64-bit Xeon processors (which were originally due at the end of 2004) and Microsoft slipping on its 64-bit Windows Server 2003 operating system and "Yukon" SQL Server database release, putting a 32-way machine in the field that could only address a maximum of 64 GB of main memory was not a good balance for the server. This is why IBM held off on delivering its 32-way machine until the Hurricane chipset was ready, Intel got the 64-bit chips out the door, and Microsoft got the 64-bit version of Windows out the door for servers. (The company is still working on getting 64-bit Yukon done, however.)

With the new xSeries 460, IBM is supporting 32-bit and 64-bit variants of Windows Server 2003 and 32-bit and 64-bit variants of Linux 2.6, specifically the Linuxes from Red Hat and Novell, which are IBM's key Linux distributors on X86-X64, Power, and mainframe servers. The xSeries 460 is based on a four-socket, 3U chassis, and to scale up to 32-way processing, it uses fiber optic interconnections to link the four-way boxes into a single system image. Like IBM's Power-based servers and prior Summit and Summit-II chipsets, the Hurricane chipsets use NUMA technology to glue multiple server cell boards together to create a single system image that looks more or less like a big SMP server to operating systems and their applications. While the Summit-II chipset was based on an eight-socket, 4U chassis, IBM decided with the current round of enterprise-class xSeries servers to use the same chassis in the xSeries 366 (a four-way that only supports the Cranford Xeons and not the Potomacs) as a building block component. Cramming eight processors and their memory in the box was possible with 3 GHz, 32-bit "Gallatin" Xeons, but with faster 64-bit Xeons that have higher clock speeds and bigger caches as well as support larger chunks of memory--and with dual-core Xeons on the way next year--IBM decided that it would be best to go a little less dense and make the thermals not so constrained with this line of xSeries products. To make a fully loaded 32-way, customers have to link together eight of these rack-mounted chassis.

The xSeries 460 supports all three variants of Intel's Potomac chip: a 2.83 GHz version with 4 MB of L3 cache, a 3 GHz version with 8 MB of L3 cache, and a 3.33 GHz version with 8 MB of L3 cache. These 64-bit Potomacs have little bit more clock performance and twice the cache of the fastest 32-bit Gallatins, but the Potomac processors can support 64-bit extended memory as well as older 32-bit modes; they also have a 667 MHz front side bus. So customers can buy the 64-bit hardware today and upgrade to 64-bit software at their convenience. The Hurricane chipset supports hot-add and hot-swap main memory as well as memory mirroring for customers who want to have the high availability in their systems. The xSeries 460 supports up to 512 GB of PC2-3200 DDR2 main memory, with 2 GB in a base configuration with a single chassis and two Potomac processors. Each chassis has six drive bays and six PCI-X 2.0 266MHz I/O slots, both of which are enabled with hot plug and hot swap capabilities.

A base configuration of the xSeries 460 costs $18,129, including the chassis, two 2.83 GHz Potomac processors, and 2 GB of main memory. Bretzmann says that the sweet spot configuration will be an eight-way box, and such a machine equipped with 8 GB of main memory, four disk drives, and a ServeRAID disk controller will sell for $72,182. (Neither of these machines are configured with an operating system in that pricing.) The eight-way version of the xSeries 460 will be available on June 17 supporting Windows, and Linux will be supported on the box within 30 days as Red Hat and Novell certify their operating systems on the platform. If you want a 16-way or 32-way configuration, these will not be available until sometime in the second half of 2005. IBM is not being more precise, which probably means in the fall. IBM is pushing VMware's virtual machine partitioning on the xSeries 460, and Bretzmann says that in many cases, virtualizing a big SMP box using a product like ESX Server makes a lot more sense than clustering a bunch of smaller servers and virtualizing them. This idea will resonate with customers used to buying big boxes and consolidating workloads. "Things are often easier and more predictable with a big SMP server," he says.

In terms of performance, Bretzmann says that IBM is readying a TPC-C online transaction processing benchmark test running Windows Server 2003 and its own DB2 8.1 database on an eight-way box that should be able to crank out 250,975 transactions per minute. It is hard to say how far a 32-way version of the machine will scale, and Bretzmann was not prepared to offer up any estimates. But it is reasonable that a 32-way box should be able to do about 2.5 to 3 times the work of the eight-way box--and might be able to do more if IBM's Hurricane chipset can reduce the latencies between memory in the nodes in the server cluster. We'll have to see. Compared to the 32-bit Gallatin servers using the Summit-II chipset from IBM, the xSeries 460 has about 60 percent more oomph, which is a pretty big jump in performance for a jump to a new server generation.

As for future scalability, don't expect IBM to push it beyond 32 sockets any time soon. According to Bretzmann, both Windows Server 2003 and Linux 2.6 top out at support for 64 simultaneous threads. With HyperThreading turned on, that means a 32-way xSeries 460 can't do any more threads running Windows or Linux. And by this time next year, Intel will be shipping and IBM will be using dual-core Xeon processors with HyperThreading that will put as many as 128 threads in a top-end 32-socket server. If the market requires it, the Hurricane architecture probably can expand more, but a 64-core Xeon server with 512 GB or 1 TB of main memory is a very big machine, and a lot more than most customers will need. The current xSeries 366 and xSeries 460 machines will support future Intel processors, by the way. "We have created an architecture that can run the next several generations of Intel chip technology," Bretzmann boasts.

IBM is also not interested in using the Opteron processors from AMD in the servers that support the Hurricane chipset, and as we reported earlier this year, Big Blue is not going to support the Itanium processor with Hurricane, either. While the Summit family chipsets had an Itanium variant, IBM believes that by tightly linking to the Xeon X64 architecture, it can build a server that meets the needs of Windows and Linux customers without having to support Itanium, too.

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