The Apple Nehalem Xserve ranks best-in-class in build quality, engineering, durability, and serviceability among 1U x86 rack servers.

The newest Apple Xserve, redesigned around Intel's Nehalem Xeon quad-core CPU, adds performance to the list of Xserve's leadership criteria. Nehalem Xserve is very likely the fastest, most energy-efficient, and most cost-effective dual-socket 1U rack server on the market.

Xserve's designers didn't need to commission a forward-looking study of enterprise server buyers to cook up the Apple Nehalem Xserve's specifications. It had only to chat with the IT leaders responsible for iTunes Music Store, iPhone App Store, MobileMe, Apple Store, and Apple Developer Connection. Apple's own requirements already reflect what analysts predict for the cloud.

Ideal cloud servers will strike a balance between low power utilisation and high reserve performance that's nearly impossible to achieve. By linking Intel's Nehalem architecture with custom system management hardware and a platform-tuned OS, Apple aimed for that server power/performance ideal and scored.

Apple Nehalem Xserve is not everything it could be; we want to see lower power consumption at idle, for example. But those who buy this server will witness it evolve in firmware and software. Apple Nehalem Xserve is a market-leading system now, and it'll be even better a year on.

The things that matter most to a massive enterprise with multiple datacenters are reflected in Apple Nehalem Xserve's feature list: a standards-based (IPMI 2.0) lights-out management controller is wired to an incomparably broad array of hardware sensors for local and remote monitoring of health and power utilisation.

By default, Apple Nehalem Xserve is optimised for headless (no monitor, keyboard, or mouse) deployment and operation. If you do need a close encounter with Xserve, most of it comes apart easily with only a Phillips head screwdriver, and its large, captive screws won't dive into your case for that familiar and frustrating game of hide and seek. Xserve weighs less than other 1U rack servers, even fully loaded, and yet it's undeniably sturdy. Xserve is a pleasure to work with at any distance.

NEXT PAGE: it starts with Nehalem

The Apple Nehalem Xserve ranks best-in-class in build quality, engineering, durability, and serviceability among 1U x86 rack servers.

Apple Nehalem Xserve: it starts with Nehalem

Apple Nehalem Xserve's marquee feature is, of course, the Intel Nehalem Xeon CPU and bus architecture. Intel pulled Xeon's formerly external memory controller onto the processor die, a shortcut that Apple claims more than doubles the effective memory throughput compared to the prior-generation Harpertown Xeon.

This claim is backed by STREAM benchmarks we've performed comparing the prior eight-core, 3GHz Xserve to the present 2.93GHz Nehalem model. The original eight-core Harpertown Xserve turned in a STREAM Triad score of 6,769MBps on a test with eight simultaneous threads, while the same binary running on Nehalem Xserve reports a Triad score of 19,065MBps.

That's no typo, and you should set aside your inclination to write off STREAM as a predictor of real-world server performance. In SPECjbb2005 (Java business benchmark) tests, the original eight-core Xserve scored 36,688 operations per second, while Nehalem Xserve managed a score of 83,926.

With only 8GB of RAM to Nehalem Xserve's 24GB, the older server was underconfigured by modern standards, a fact that may have contributed to its poor showing despite the fact that the machine did not resort to paging processes out of RAM during testing. Poor scalability under parallel memory-intensive loads was a characteristic of Intel x86 pre-Nehalem, symptomatic of a bus architecture that imposed a heavy penalty on memory access. That penalty is gone.

The smooth scalability of Apple Nehalem Xserve under rising parallel load in the SPECjbb2005 tests not only highlights the Nehalem architecture's improvements, but also Mac OS X Leopard Server's exploitation of the architecture. The kernel's deft assignment of tasks to processor cores and thread units, and its mapping of physical memory to leverage NUMA (non-uniform memory architecture), keeps Nehalem Xserve's six memory channels working together.

It took Microsoft several years to fix Windows Server to make appropriate use of AMD64 NUMA, the model Intel adapted for Nehalem. If early benchmarks are any indication, Apple seems to have gotten NUMA right on its first try.

NEXT PAGE: ecofriendly?

The Apple Nehalem Xserve ranks best-in-class in build quality, engineering, durability, and serviceability among 1U x86 rack servers.

Apple Nehalem Xserve: Ecofriendly - to a point

The 2.26GHz Apple Nehalem Xserve is probably the greenest server this side of UltraSPARC T2, and for many uses, it will outperform the eight-core, 3GHz model it replaces.

Xserve meets Apple's exacting standards for environmentally responsible manufacturing - it's so non-toxic that it's practically edible - but in its maxed-out 2.93GHz, eight-core incarnation, Nehalem Xserve is more about high speed than low power. Mac OS X Leopard Server lacks the equivalent of Windows Server's energy profiles. There's no way to make the server less than it is for the sake of enhancing savings and quiet at times of low compute demand.

The new Xserve's power draw at idle is higher than that of the previous Xserve. That said, Xserve makes a greater effort than most rack servers to run as quietly as its workload permits. The fan array can get loud, but Xserve never emits the piercing high-frequency din that high-end 1U rack boxes can broadcast. Nehalem Xserve's noise is very effectively muffled by my GizMac XRackPro.

One power-saving option holds great appeal for shops that make heavy use of networked storage. Apple now sells a 128GB solid-state (flash) boot drive for Xserve. This can greatly reduce power consumption, heat, and noise, and with no seek or rotational latency, the system loads the kernel and apps lightning fast.

This comes at the expense of write speed, though. With its plentiful cache, further abetted by the cache on the server's optional hardware RAID controller (highly recommended), a single 1TB Western Digital SATA drive was two to three times faster in write performance than the SSD. Look to the solid-state drive option to simplify and slim your Xserve, not to speed it up.

The lack of power controls is a shame because no x86 server is better equipped to make smart decisions about power than Xserve. The temperature, voltage, and current draw of most major components are tracked continuously and reported to Xserve's independent system management controller, which Apple calls the "LOM" for "lights-out management".

LOM data is readable with Apple's Server Monitor GUI or the ipmitool command-line utility. The LOM shares one of Xserve's two gigabit Ethernet ports, using its own IP address and security credentials.

Xserve's LOM is limited in comparison to other servers' baseboard management controllers. When the system is powered down, it functions primarily as a remote power switch and a means to select the source of the boot image.

The LOM lacks the ability to remotely control the console (KVM over IP), although ipmitool provides rudimentary, unofficial "serial over LAN" support. The LOM's field replaceable units (FRU) inventory capability is not used, and motherboard sensor status is unavailable, even in cached form, when the system is powered down.

The Apple Nehalem Xserve ranks best-in-class in build quality, engineering, durability, and serviceability among 1U x86 rack servers.

Apple Nehalem Xserve: Deal or no deal?

We came to this review with three questions in mind: is Nehalem Xserve better than Mac OS X Leopard Server running on Mac Pro? Do existing Xserve owners have a compelling reason to upgrade? And finally, does Nehalem Xserve give users of other brands of rack servers cause to consider a switch?

The first question is one of value. Someone running one to three servers is less likely to be concerned about lights out management, redundant power supplies, the rack form factor, and spare parts kits, key Xserve features with large-scale IT appeal.

Next to Nehalem Xserve, Nehalem Mac Pro is the far greener and quieter machine, with more room for storage and a matching hardware RAID option. However, Mac Pro has less RAM capacity, and solid-state storage isn't an option (at least not from Apple). People using Mac Pro as a pedestal server also get the advantage of adding storage with raw SATA drives, an option that Apple precludes on Xserve.

Existing Xserve owners need to upgrade to the Nehalem model, if only because the enormous leap in memory bandwidth makes it possible to do so much more work in the same space. Nehalem and Mac OS X seem positively made for each other; neither is as impressive alone as it is with the other. It's a certainty that Snow Leopard, when it ships this summer, will be at its best on Xserve. Apple built a discrete GPU with dedicated memory into Xserve to take advantage of Snow Leopard's ability to parcel out compute tasks to the 3-D accelerator.

As for whether Nehalem Xserve is strong enough to pull newcomers to the Mac server platform, that's hard to say. It probably should, but Xserve is an odd duck. IT is conditioned to look at x86 rack servers as raw material for handmade solutions. Xserve is a solution in itself, but a review of the hardware fills in only half of the picture. Making an intelligent choice about a Mac server platform requires familiarity with Mac OS X Server.

NEXT PAGE: our expert verdict >>

Apple Nehalem Xserve: Specs

  • 2.26 GHz Quad-Core Xeon 5500 series processor with 8MB of fully shared L3 cache
  • 3GB of 1066 MHz DDR3 ECC RAM
  • a single 160GB 7200 rpm SATA Apple Drive Module
  • dual Gigabit Ethernet on-board
  • two PCI Express 2.0 x16 expansion slots
  • Bonjour-enabled Lights-Out Management processor and Server Monitor Software
  • internal graphics with Mini DisplayPort output
  • two FireWire 800 and three USB 2.0 ports
  • an unlimited client licence for Mac OS X Server version 10.5 Leopard
  • 44x447x762mm
  • 14kg base configuration
  • 2.26 GHz Quad-Core Xeon 5500 series processor with 8MB of fully shared L3 cache
  • 3GB of 1066 MHz DDR3 ECC RAM
  • a single 160GB 7200 rpm SATA Apple Drive Module
  • dual Gigabit Ethernet on-board
  • two PCI Express 2.0 x16 expansion slots
  • Bonjour-enabled Lights-Out Management processor and Server Monitor Software
  • internal graphics with Mini DisplayPort output
  • two FireWire 800 and three USB 2.0 ports
  • an unlimited client licence for Mac OS X Server version 10.5 Leopard
  • 44x447x762mm
  • 14kg base configuration

OUR VERDICT

Apple's Nehalem Xserve packs more into one rack unit than any other server. For one price, you get a best-in-class server and a commercial Unix OS with unlimited client licences, plus a foolproof management GUI. The 2.26GHz eight-core model outguns and out-greens the original 3GHz, eight-core Harpertown Xserve if you fill it with RAM.

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