NEC, Stratus Flesh Out Fault Tolerant Server Lines

Published: July 25, 2007

by Timothy Prickett Morgan

Back in March, partners NEC and Stratus Technology previewed a two-socket fault tolerant server that was based on Intel's quad-core "Clovertown" Xeon 5300 processors. Last week, that box has started shipping, and the two companies are also starting to take orders for smaller configurations of their fault tolerant machines, which are based on Intel's dual-core "Woodcrest" Xeon 5100s and which come with one or two logical sockets per server.

Under a 10-year partnership that the two companies announced back in November 2005, Stratus and NEC have pooled their resources to create a single fault tolerant server hardware line, with NEC actually making the gear from modified versions of its X86-based and now X64-based Express5800 series of rack-mounted servers. These designs have a lot of Stratus intellectual property in them. Stratus and NEC have been partners since 1990, when NEC inked a deal to resell the Unix/CISC fault tolerant platforms created by Stratus--and sold primarily against Tandem Computer's Himalaya and earlier fault tolerant servers. (IBM was also a reseller of Stratus gear for many years, selling the machines as the System/88.) The VOS variant of Unix created by Stratus is still supported on its Continuum line of servers, which are based Hewlett-Packard's PA-RISC processors. (HP has long since shifted to Itanium processors and has not had the PA-RISC chips in development for many years.) NEC is an investor in the privately held Stratus, and the two are working to create fault tolerant products that bring the benefits of machines like the Continuum line of servers to something that looks and feels a lot more like a general purpose X64 servers, even if it does have a slightly different architecture.

No matter what processor a fault tolerant server uses, the design is basically the same. Two physical servers are connected at their main memory and they are logically a single machine, running mirrored copies of the same exact operating system and stack of software. Therefore, they process exactly the same transactions in absolute lockstep. Should one machine in a pair fail, end users never see it because the transactions just keep going. The key component in this setup is called the FT Crossbar, which cross connects all of the components in both machines so that the failure of any one or many components has no effect on the running of applications. This crossbar is implemented in an NEC chipset called the GeminiEngine.

This is not the same as high availability server clustering, where two separate machines are equipped with two distinct operating systems and two sets of application software; clustering and data replication software enables applications to failover from a production machine to a backup box in the event that the production machine crashes. But it takes time to do that roll swap, and you have to be mindful to keep your data replicated between the two machines or else you can lose transactions.

As previously reported, the Stratus ftServer 6200 and NEC Express5800/320Fc servers that were previewed in March and are shipping now are essentially the same iron. Each company supports different operating systems, provides their own variants of systems management and monitoring software, and has its own sales channel. The servers are based on a 2.66 GHz Clovertown chip, which has a 1.3 GHz front side bus and 4 MB of cache per core. The servers have two logical sockets (two physical sockets in two physical servers) and support from 4 GB to 24 GB of logical main memory for applications. (You have to use relatively pricey 4 GB DDR2 DIMMs to get the maximum memory.) Each chassis in the two-chassis fault tolerant complex has room for three SAS or SATA disks, and EMC's Symmetrix and Clariion disk arrays are certified to provide external storage to the machine when it is running Windows. Stratus is also selling ftScalable Storage arrays to customers who want these, which support Linux as well as Windows. Each chassis in the FT pair has six PCI-X slots, or four PCI-X slots and two PCI-Express slots if customers want to go that way.

Stratus is supporting the 32-bit implementation of Windows Server 2003 Enterprise Edition on the ft6200 and so is NEC on its Express5800/320Fc. According to Stratus, 64-bit versions of Windows will be supported on this machine in a matter of months, with Red Hat Enterprise Linux 4 AS running in 32-bit or 64-bit mode coming in September for these servers.

The new entry fault tolerant box from these partners is called the ftServer 2500 by Stratus and the Express5800/320Fc-LR by NEC. This machine has a single processor socket supporting Intel's dual-core Xeon 3100 series of chips (a variant of Woodcrest for single-socket boxes) running at 2 GHz; the motherboard in each chassis has six memory slots, but only supports 1 GB DIMMs for some reason, limiting main memory from 2 GB to 6 GB. The machine supports the same peripheral slots and external storage. Windows Standard Server 2003 running in 32-bit mode is available now on this machine, with 64-bit support coming in a few months along with RHEL 4 AS.

The middle machine in the FT server lineup from Stratus and NEC is the ftServer 4400 or the Express5800/320Fc-MR, respectively. These machines have two processor sockets in each logical box, and customers can put one or two 2 GHz Woodcrest Xeon chips inside. This server has the same peripheral expansion as the other two, but supports either 1 GB or 2 GB DIMMs. Windows Server 2003 Enterprise Edition running in 32-bit mode is available today on these servers, followed by 64-bit Windows and RHEL 4 support in September or so.

NEC is pricing the base Express5800/320Fc-LR at $18,000, while the Express5800/320Fc-MR costs $26,000. Stratus is charging $12,500 for the ftServer 2500 in a base configuration, and the ftServer 4400 costs $21,250 in a base configuration. NEC and Stratus are putting different things in the base boxes, so the comparison is not apples-to-apples. These prices include one logical processor, base memory, no disk, no operating system, and none of the additional system management tools that NEC and Stratus want to sell to FT customers.

As reported earlier, neither company has any interest in making an FT server line based on Advanced Micro Devices' Opteron processors, and they are similarly uninterested in using Intel's Itanium processors or its 64-bit "Tulsa" Xeon MP machines to create larger systems.

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