Stratus Debuts First Fault-Tolerant Linux Server

by Timothy Prickett Morgan

Fault tolerant server maker Stratus Technologies today announced the first in what it says will be a full line of Linux-based machines that bring the resilience it created for high-end Unix machines in the 1990s and ported to Windows 2000 and Windows 2003 in the past several years to its own variant of the open source Linux 2.4 operating system running on Intel's 32-bit Xeon DP processors.

The naming of the ftServer T Series seem to reflect who Stratus is aiming the machines at: "T" is for telecommunications, and the first customer to buy one of the new servers is LG Electronics, the Korean telecommunications equipment maker that is selling what Stratus says is a major soft switch application that will be launched by Korea Telecom.

The ftSerer T30, the first in the series, has two logical processors (which means it has four physical ones). Each of these processors is a 2.4 GHz "Presontia" Xeon DP with 512 KB of L3 cache. The maximum addressable application memory (which is also redundant) is currently 4 GB, but Stratus says it will boost that to 6 GB in a future release of the platform. The ftServer T30 has six PCI slots, with four of them usable by the user for peripheral interconnect (the other two are used for the ft Access Adapter cards that link the two nodes in the fault tolerant cluster). Each ftServer T30 has six drive bays, and Stratus is supporting 36 GB and 73 GB SCSI disks spinning at 10K RPM and 18 GB disks spinning at 15K (the latter being for performance-oriented customers). The company says it will support more capacious disks in that future T30 kicker as well, which probably means 146 GB SCSI disk drives. The server has four embedded Ethernet NICs, two running at 100 Mbit and two running at 1 Gbit. These machines run a customized version of the Linux 2.4.18 kernel, a very stable release of Linux, which Stratus has hardened and extended to take advantage of the substantial expertise that Stratus has in building computers that are highly available.

While these machines bear a strong resemblance to the ft5600 fault-tolerant Windows servers that Stratus announced last year, they are really aimed at displacing aging Stratus Continuum servers running Hewlett-Packard's HP-UX that the company sold in droves to telecom companies and financial services institutions over the years. The special hypervisor layer that Stratus ported from its Continuum line of Unix fault tolerant machines, so it would work with Windows 2000 Advanced Server and Windows 2003 Enterprise Edition, has been ported to Linux 2.4. This, coupled with the adapter cards, is the secret sauce that is so hard to duplicate.

Stratus says that the ftServer T Series line will eventually be upgraded with a more powerful machine, which will probably look very much like the ft6600 server that the company sells supporting Windows and using "Gallatin" Pentium 4 Xeon MP processors. The ft6600 is a logical four-way that uses 2 GHz or 2.8 GHz processors and supports from 2 GB to 12 GB of main memory. It is actually two four-way machines linked by Stratus hardware and software to look like that logical machine.

Fault tolerant machines, like the Stratus ft and Continuum lines or HP's NonStop (Tandem) server line, have double or triple redundant components that allow data processing to continue even when one of the components fails. This makes the machines doubly or triply expensive, but it also gets availability up over five nines and approaching six nines.

While LG Electronics is getting its ftServer T Series machines today, they will not become generally available until sometime in May. Stratus has not announced pricing on the boxes, but the Linux-based machines should not cost appreciably more than the Windows-based ftServers. Stratus has been developing the Linux ftServers since the summer of 2001, when it hired its first programs to create the hypervisor layer for Linux. This is difficult and tedious work, which is why Stratus has not announced a variant of the new Linux 2.6 kernel on these machines.