Apple has released a major update to its rack-mounted Xserve, taking advantage of the significantly increased processing power of the latest Intel "Nehalem" Xeon processors and new system architecture used in the recently refreshed Mac Pro (see "New Mac Pro Uses Intel 'Nehalem' Xeon Processors," 2009-03-03).
Power-saving and performance-enhancing technologies that first saw the light of day in the Mac Pro should be especially welcome in the Xserve, whose non-stop use makes power savings important. In particular, TurboBoost enables the Xserve to shut down idle cores and boost the clock speed of active cores, and Hyper-Threading allows two threads to run simultaneously on each core, providing a more-efficient use of resources without needing more physical (and thus power-consuming) cores. Thanks to the new processors and architecture, Apple is claiming an 89 percent improvement in performance per watt over the previous-generation Xserve and a 19 percent reduction in idle power use.
The new Xserve comes in two basic configurations, a quad-core model with one 2.26 GHz quad-core Intel Xeon processor for $2,999 and an 8-core model with a pair of 2.26 GHz quad-core Intel Xeon processors for $3,599. The 8-core model can be upgraded to a pair of 2.66 GHz Xeon processors for $1,400 or a pair of 2.93 GHz Xeon processors for $2,600. Each processor has 8 MB of shared L3 cache and its own three-channel integrated memory controller to reduce memory latency and improve performance.
Both Xserve models default to 3 GB of 1066 MHz DDR3 ECC RAM, but the two models differ in RAM expansion options. The quad-core model has only 6 DIMM slots for RAM. Apple's maximum build-to-order configuration maxes out at 12 GB. The 8-core model has 12 DIMM slots, but Apple will sell you only up to 24 GB of RAM, not the full 48 GB that would theoretically be supported. That may be because Mac OS X Server 10.5 supports only 32 GB of RAM; I suspect that limit will disappear in Snow Leopard Server.
The Xserve ships by default with a single 160 GB SATA Apple Drive Module in one of three drive bays. For the moment, the Apple Store allows you to configure an Xserve only with either a 160 GB SATA ADM or a 1 TB SATA ADM, but the onboard SATA/SAS controller also supports 15,000 RPM SAS drive modules. Oddly, you must buy SAS ADMs separately from the Apple Store, which seems like an unnecessary hassle. As before, you can replace the SATA/SAS controller with an Xserve RAID Card for $700. For more information about Apple Drive Modules, see "Going Deep Inside Xserve Apple Drive Modules" (2009-03-27).
But what's innovative about the new Xserve in terms of storage is an optional 128 GB solid-state drive for $500. If added to the Xserve, the 128 GB SSD is automatically configured as the boot drive and doesn't take up one of the Xserve's drive bays. According to Apple, the SSD consumes less than 1 watt of power, compared to 12 to 18 watts for typical drives. Plus, the SSD reportedly features random-access performance that's up to 20 times faster than a SAS drive and up to 48 times faster than a SATA drive. Apple makes no claims about reliability, but it would also seem likely that the lack of moving parts would make a solid-state drive less prone to hardware failures; perhaps there isn't yet enough data to say that about SSDs.
Video support on the Xserve is now provided by the Nvidia GeForce GT 120 with 256 MB of GDDR3 memory. In keeping with Apple's model-line push, the Nvidia card offers only Mini DisplayPort output, thus requiring adapters - sold separately - to connect to VGA or DVI monitors.
Relying on Mini DisplayPort in the Xserve feels like a mistake, since no data center will be using Mini DisplayPort-equipped monitors. Chuck Goolsbee of the Web hosting and colocation firm digital.forest, agreed, "Switching to Mini DisplayPort for video is unwise, as no KVM sold today is Mini DisplayPort-compatible. That means adapters will be required, adding to the costs of deployment and complicating troubleshooting, which often is done remotely."
Other standard features include an unlimited client version of Mac OS X Server 10.5, an 8x SuperDrive, two PCI Express 2.0 x16 expansion slots, two independent gigabit Ethernet ports, two FireWire 800 ports, two USB 2.0 ports on the back and one on the front, and a DB-9 RS-232 serial port. Dual redundant power supplies remain optional.
Physically, it appears that Apple chose not to respond to criticisms of the Xserve industrial design, making the new Xserve nearly identical to the previous Xserve (see "New Xserve Goes Eight-Core Too," 2008-01-08). Digital.forest's Goolsbee commented, "Apple hasn't addressed the weaknesses of the Xserve's case design compared to similar offerings from competitors in the server space. It's still way too deep, and it still lacks a video port at the front of the unit."
The Xserve's 30-inch (76.2 cm) depth forces awkward spacing in standard racks, and the lack of front-mounted video (and FireWire) ports complicates arranging Xserves in "hot" and "cold" aisles that provide significantly more-efficient cooling. (Arranging servers such that adjacent aisles have the backs of servers facing each other creates a "hot" aisle that can be contained from the front-facing "cold" aisles. With contained "hot" aisles, requiring user access to the back of the Xserve is troublesome, both for the technicians doing the work and for maintaining the cooling.)
This isn't rocket science - many, if not most, rack-mounted servers from the likes of IBM, Dell, and HP replicate user-focused ports like USB, video, and FireWire on both the front and back panels, and relegate system-focused ports like Ethernet and power to the back panel.
Overall, the new Xserve offers extremely welcome performance improvements, and it's excellent to see Apple putting so much thought into reducing power requirements at the system architecture level. Plus, the optional solid-state drive is a fabulous addition. But it's too bad that Apple didn't rethink the Xserve's physical design with regard to the overall environment in which Xserves commonly operate.