IBM x450 offers high-density, so-so performance

In the dog-eat-dog world of commodity, Intel-based servers, IBM’s eServer xSeries 450 is a greyhound. As is often the case with such purpose-bred creatures, IBM’s lean and svelte rack-mountable 64-bit solution sacrifices computing heft (lots of memory and expansion possibilities) in favor of another worthwhile quality — a smaller footprint.

In fact, the xSeries 450’s 4U rack space requirements are one of IBM’s primary marketing bullets for this system, which is matched only by IBM’s x455 and rival Hewlett-Packard’s Integrity rx4640 in delivering a four-way capable IA-64 system in a 4U form factor. Hewlett-Packard also offers a four-way IA-64 system in a much larger 7U package, the Integrity rx5670, delivering greater memory expansion (96GB vs. 40GB for the x450 and 56GB for the x455) and using speedier PC2100 DDR (Dual Data Rate) ECC (Error Correcting Code) memory (the xSeries use slower ECC SDRAM).

IBM makes up for some of these shortcomings by innovating in other areas, such as fault isolation. The x450’s intuitive Light Path Diagnostics feature makes it easy to trace a fault to its source, with internal LEDs leading you from the front panel display straight to the failing component.

This process is further aided by the modularity of the xSeries. Major functional areas (CPU, memory, I/O) are grouped into quick-release component blocks that make it easy to gain access to the innermost regions of the chassis. In fact, the system is so well laid out, and the on-chassis diagrams so straightforward, I was able to break the entire server down to its base frame in just a minute or two without any tools.

Of course, the xSeries also ships with the core redundancy features that enterprise IT customers expect: dual hot-swappable power supplies; hot-swappable cooling fans; six hot-swap/add PCI-X slots (HP offers nine in the rx5670); Chipkill memory fault isolation; and Active Memory technology, which IBM claims is like RAID for memory. In fact, you get nearly everything you’d want in an Intel-based server. My only major gripe is with the memory subsystem: not enough expansion and (potentially) reduced performance with SDRAM, which IBM denies.

Itanium vs. Xeon

Whether or not the slower SDRAM was a factor in my test results is difficult to say. The xSeries 450’s performance was adequate but unremarkable under 64-bit versions of Windows Server 2003 and SQL Server 2000 in my tests. In two- and three-tier client/server database simulations, the x450, with its two 1.5GHz Itanium 2 processors, outpaced a similarly equipped Xeon server, IBM’s xSeries 335 with dual 3.06GHz Xeon DP processors, when running identical workloads. However, the margin of victory was small — just 5 to 8 percent.

Due to the relative immaturity of the 64-bit Windows Server 2003 code base, I hesitate to blame any performance shortcomings on a particular hardware implementation. However, the x450 demonstrated similarly ho-hum performance in separate tests under Linux, where it was equaled or outpaced by the dual Xeon x335 in a number of tasks. A MySQL benchmark showed the x450 lagging behind the dual-Xeon x335 in several tests, notably table inserts. Overall, the MySQL tests showed the x335 besting the x450 by about 10 percent on average, whereas Samba filesharing tests showed the x450 faster by about 8 percent.

Some of these results could be skewed by specific server code optimizations, so I’m reluctant to call the xSeries 450 an underachiever. Furthermore, where application requirements demand 64-bit addressing (such as with massive in-memory databases or complex floating-point operations), the capabilities of the x450 far outstrip those of a Xeon-based server. In these scenarios, there really is no substitute for an 18 Exabyte (2^64) flat address space.

The xSeries 450 achieves IBM’s stated goal of delivering Itanium 2 capability in minimal space. But along the way, Big Blue was forced to make some tradeoffs in terms of expandability and component selection (SDRAM). It may be too early to tell how well the xSeries 450 will perform with a well-tuned software stack. What is certain is that IBM has done its homework in making the x450 easy to maintain, with innovative technologies such as Light Path Diagnostics helping to differentiate this offering in an increasingly crowded IA-64 field.

Paul Venezia contributed to this review.