Apple Xserve: The final review

As usual, Apple knows something that its competitors don’t, and after three weeks with Apple’s new Xserve and OS X Server Tiger 10.4.8, I know it, too. Apple is taking a road that pundits will likely insist will lead Apple nowhere: It is doing a server appliance play, but not of a flavor that the market’s seen before. While trends, or rather, the analysts who proclaim them, are pointing to the triumph of software as a service, outsourced applications, consulting, node-locked operating systems and other pay-as-you-go approaches, Apple is piloting a rocket-powered sled in the opposite direction.

Apple is going to sell complete server platforms that buyers purchase, operate themselves and actually own. Seriously. The customer pays the advertised price for an Xserve (starting at $2,999) and gets a server loaded and pre-configured with a server software suite (PDF) that alone meets the needs of the majority of Intel x86 rack server buyers. There are no subscriptions, no priority update service fees, and no client, device, mailbox or CPU licenses. None of the services is grayed out pending your purchase of an unlock key. Xserve has no try-and-buy, no time bombs and no trip wires telling you that you need to upgrade from Express this or that to Professional this or that. Xserve never phones home to beg for Apple’s permission to use the server software already loaded on your system. And if Apple played the slick pricing games that its competitors do, Xserve’s advertised price would be $2,000, with a one-item selection menu on the Buy Now page that reads “OS X Server, unlimited users (+$999).”

Xserve is an Intel x86 Xeon computer, and on its own, it represents exemplary hardware engineering. You’ll find my detailed review of Xserve hardware in a previously-posted part of my review. To summarize, in designing Xserve, Apple had more in mind than making a standard Intel x86 server (with the standard defined as “able to run Windows,” to which Xserve will stoop if so commanded). Instead, Apple engineered its quad-core Core microarchitecture Xeon server–which it could have purchased off the rack for $0 in R & D–to be an entry-priced server that meets the requirements of mid-level server buyers. In durability, serviceability, manageability and availability, Xserve more readily finds rivals among UNIX RISC servers than commodity Intel x86 systems.

Xserve is the new flag-bearer for the total Apple server platform, which encompasses Xserve, OS X Server, the Xserve RAID storage array, the Xsan SAN file system and the WebObjects large-scale server application framework used for iTunes and most of apple.com. While Xserve the computer more than holds its own among PC servers in its price class, it is the one-price combination of Xserve and OS X Server that dusts the competition.

Xserve strikes the perfect chord with everyone from the server neophytes and Windows refugees who want plug and play to the UNIX graybeards allergic to proprietary system software, equipment or development tools. Freed from the never-ending spending of Windows and the do-it-yourself shipbuilding of Linux, every single buyer of Xserve will end up doing more with Apple’s server than they had in mind when they bought it. Apple makes it safe and simple to reach beyond the narrow purposes for which individual Windows and Linux servers are typically deployed. Xserve can run its full range of services–which include Web, database, J2EE, e-mail, anti-virus, IM, Windows and UNIX file/’print sharing, VPN, gateway, proxy, and firewall.

Xserve is uniquely easy to deploy and manage on its own or as part of an established heterogeneous network of systems, and yet it is not dumbed-down in the least. It carries the traditional benefits of Apple’s “invented here” design, particularly the rock solid stability that OS X derives from being targeted to a limited number of controlled configurations (note that OS X Server runs on client Macs as well). And yet Xserve is an entirely standards-based, open design, but with none of the prefab, seen one seen ’em all engineering that typifies Intel x86 servers.

An appliance for some, a wide-open UNIX platform for others

Unlike other Intel OEMs’ boxes, Xserve ships from Apple as a complete server platform, not as a computer. The difference? A server platform is a whole–hardware, OS, standardized services, GUI management, dev tools, server application frameworks, documentation and much more–that emerges from its shipping carton with functionality that fully satisfies the needs of the majority of buyers. When I plugged Xserve in for the first time, it did what I expected: It gave me my choice of services including, but not limited to, Web, database, J2EE, e-mail, blog, IM, Windows and UNIX file/’print sharing, gateway, proxy and firewall. It took about three minutes, with no reboot, to put my services on the air, and they were all immediately configured, reconfigurable and reporting to Apple’s Server Manager and Server Monitor GUI consoles.

Linux users are accustomed to wading through several pages of checkboxes to select from among the bulging sack of software–some maintained, some not–burned onto the install DVDs. OS X Server doesn’t subject users to that. If you ask for e-mail services, OS X Server sets up the open-source SMTP, Web mail, spam filter, virus checking and list management that Apple selected, validated and, in some cases fixed and enhanced (always giving its changes back to the projects). Apple isn’t reticent to count and credit the projects are part of OS X Server. However, by default, projects and versions are abstracted by the install and management interfaces. That abstraction allows administrators to treat each major network service category as an integrated solution rather than a stack of pieces. Server Manager, the multi-server administrative console bundled with OS X Server and available as a free download for running on client systems, presents a unified interface that eliminates the need to configure each mail service component individually and deal with instabilities that arise from conflicting configurations. Apple brings this consistent, centralized approach to the Server Monitor console that handles Xserve hardware monitoring, reporting and notification.

Now, if you’re nauseated by the notion of using a novice-friendly server appliance, Apple feels you. OS X Server’s cozy GUI desktop and management tools co-exist with–not replace–the OS X Server platform’s nuts and bolts UNIX-ness. Xserve will boot to a UNIX VGA text console, to the server’s serial port or headless (no human interface devices attached). Xserve can be administered and configured entirely from the command line and script code. And nearly all of the non-user-facing pieces of OS X Server are available as Apple-supported open source published as Apple’s Darwin project. Apple’s development tools and documentation are free, and like OS X Server, the dev tools have consistent and well-integrated graphical interfaces that you can shove out of the way if you feel like roughing it. Is Apple’s Aqua interface too dressy for you? Start X Window Xserve is a whole platform, but it is an infinitely malleable whole that you’ll find familiar and not at all confining if you’re a veteran of UNIX or Linux. I have yet to find a well-maintained open source project that doesn’t list OS X or Darwin (the open source OS on which OS X is built) among its explicit build targets. Two massive open source repositories, Fink and Darwinports, track and package OS X/Darwin compatible projects. As a UNIX box, Xserve not only fast, familiar and standards-based, it is addictive.

Xserve from the outside

Xserve is a 1U, 1.75-inch tall rack server. Its chassis is made mostly of very stiff aluminum, with steel used where extra strength is needed (like the rack rails). Its cooling system is simple and effective: Two huge rectangular, grille-less intake ports, which Apple calls “chunnels,” are set between the three removable drive bays. The remainder of Xserve’s front panel is sparse. The interactive controls consist of a power button, a chassis/drive bay lock and a system identify button that lights an LED on the back panel to make it easier for someone working at the back of a large cluster of Xserves. The system ID light can also be activated remotely from Apple’s server management GUI. The front panel buttons serve as stand-ins for a keyboard when Xserve is running headless. Patterns of button presses can, among other things, force Xserve to boot from the optical drive or from a network image.

LED indicators at the front panel are arranged and colored to make their purposes obvious: Main power, hard drive power and activity and the blue LED array that reports the CPU utilization for each of Xserve’s four cores. The Ethernet link lights tipped me off to a small but potentially frustrating anomaly: Xserve’s Ethernet ports are flipped. This becomes important when you have to configure lights-out management. For lights-out, channel 1 is the right Ethernet socket, and channel 2 is on the left when looking at the system from the rear. As a workaround, Apple recommends that you install Xserve upside down (no it doesn’t).

The front panel also has the opening for the slot-loading optical drive, which can optionally be a Superdrive dual-layer DVD burner. OS X still lacks packet writing and DVD-RAM support, so you can’t mount a disc as a read/write volume. Still, many users, myself included, find the built-in burner to be a blessing. Lastly, the front panel has the 400 Mbps FireWire socket for which Xserve administrators have 100 uses. It lets you use Target Disk Mode to mount external Macs’ local storage as drive volumes, and Xserve can be a Target Disk Mode target for another Mac as well. FireWire also works as a secure, self-configuring point to point TCP/IP link, and of course, it can be used with FireWire video and audio devices and with external FireWire storage. My pet use for Xserve’s FireWire is running Apple Remote Desktop. For most uses, this is as fast as a locally-connected keyboard and display.

Xserve’s rear panel is dominated by Apple’s power supplies. If you opt for redundant supplies, you’ll have two AC sockets to fill. However, Xserve does not sound an alarm if you set the second supply up as a cold spare by not plugging it in. By default, the second power supply constantly splits the load with the first. There’s no switching delay at fail-over, and in the event that an unexpected power burden threatens to drive the voltage on the critical +5V rail low, the supplies will compensate. Each slim, lightweight power supply has its own fan that is monitored and speed-controlled by Xserve’s System Management Controller. When you remove one power supply, an internal “doggy door” swings down to close the hole.

The rest of Xserve’s backside is a continuous grille. A strip across the bottom provides access to a DB9 serial port, a mini-DVI display connector, USB 2.0 ports, 800 Mbps FireWire and two gigabit Ethernet ports. As I mentioned, Xserve will boot to a local serial console. Apple has not yet equipped its lights-out management with the serial-over-LAN feature that would redirect that serial console traffic to an arbitrary network destination. The serial port is also used for uninterruptible power supply (UPS) units that notify connected systems of their power state. You can have the serial console or the UPS hooked to the DB9 connector, but not both. Fortunately, most standalone UPSes now come equipped with USB connections.

There are only two USB ports behind Xserve. This proved to be one too few in my testing, and I wished that there were a USB port on the front panel for human interface devices. The 800 Mbps FireWire port is conceivably useful for external storage, although there aren’t many devices that use it. The fast FireWire port’s value in my eyes lies in Target Disk Mode, Remote Desktop and dedicated server-to-server TCP/IP links. If you prefer, an 800-to-400 adapter cable will turn the high-speed port into a standard 400 Mbps FireWire port.

The mini-DVI connector uses a pigtail to connect to either an analog or digital display. Both pigtails are included, and the mini-DVI port, though tiny, is very sturdy and grips the connector well. The weight of the VGA or full-sized DVI plug at the other end poses no problem. Xserve’s standard on-board GPU (graphics processing unit) is an ATI Radeon X1300 with 64 MB of dedicated video RAM. That’s pretty sweet by server standards. It supports Quartz Extreme, Apple’s accelerated graphics, and driving OS X’s GUI at a graphical console is a pleasure. An upgraded card with 256 MB of video RAM is available, but this occupies one of the system’s PCI Express expansion slots and generally heats things up. Don’t get it if you don’t absolutely need it.

Lifting Xserve’s lid

Apple, long known for fancy zoned, heat-piped cooling designs, went for simplicity with Xserve. A wide bank of seven fans, each with dual independent rotors, stand in straight-line formation behind the drive bays. Except for the power supply fans, this long bank of fans produces the only airflow through Xserve. Thermal sensors are scattered around the system board, busses, memory sockets, CPUs and everywhere a temperature is worth taking. Instead, all of the inflow fans, the front-facing rotors, spin up and down in sync. The rear-facing outflow fans run at another synchronized speed.

A thin plastic shield covers the CPUs and creates a couple of broad airflow paths. The shield is flimsy and the screws holding it in place could be used for eyeglass frames. They’re vibration-proofed by miniscule rubber washers that you will lose if you don’t know they’re there (but now you do). It’s hard to wedge the shield back in; the right edge of the shield catches on a wire bundle. Finesse it, don’t force it, and I advise using a gently magnetized sharp-pointed Philips screwdriver to remove and replace the shield.

Beneath the shield is where the action is. The standout is a pair of tall, all-copper heatsinks. PC enthusiasts and system builders treat these like diamonds, and if you can find them at all, they are seriously expensive. They’re the only way to do what Apple’s done, and that’s run a pair of 3 GHz, dual-core Core microarchitecture Xeon CPUs without high-RPM dedicated fans. Apple’s approach works: Under maximum stress, the CPUs are among the coolest components on the system board according to Apple’s sensors. The heat sinks are attached to the system board with two large screws. Remove these and the Xeon chips in their ZIF (zero insertion force) sockets are yours for the swapping. Any desire you have to upgrade your Xserve CPUs (there is, at this writing, nothing better than the 3 GHz Xeon) must be tempered with the knowledge that Apple doesn’t promise to support user-upgraded Xserves. However, if Apple had made its CPUs inaccessible, I’d have slammed the whole machine for messing with owners’ rights.

Xserve has eight sockets for fully buffered DIMMs (dual in-line memory modules). The system I’m evaluating is stuffed with 8 GB, using 2 GB modules. There are Intel x86 servers with sixteen DIMM sockets. Why not sixteen sockets? I think that Apple made a design choice to conserve that real estate for a second power supply and a more serviceable interior layout. Apple had the advantage of entering the market when 2 GB memory modules were more readily available. For a long time, the only realistic way to squeeze 16 GB of RAM into an Intel x86 server was to install sixteen 1 GB modules. Xserve’s RAM is readily user-upgradable. Apple sells memory modules, and it offers guidance on choosing modules from third parties.

The other noteworthy feature inside Xserve is the monolithic backplane into which removable drive modules plug. Each port in the backplane supports either a Serial ATA (SATA) or Serially Attached SCSI (SAS) drive. The Apple-proprietary drive trays and rear connectors are identical regardless of interface type. SATA is plenty fast enough for local storage, especially with OS X Server’s software striping and mirroring. But sometimes an application calls for a 15,000 RPM SCSI device. Put SAS speed where you need it, and SATA capacity everywhere else. It’s worth noting that Xserve’s Apple Drive Modules are not compatible with Mac Pro, and Apple does not sell empty trays for Xserve. You can, however, upgrade a drive in an Apple Drive Module quite easily. Apple doesn’t acknowledge this, but does claim that it optimizes drive firmware for server operation. Apple’s hard drive mark-up is reasonable, so it’s probably not worth the bother to put a new drive in an old tray. Like the CPUs, the fact that Apple didn’t explicitly block you from using raw drives points to Apple’s commitment to an open, standardized approach.

Xserve’s environmental impact

Computers need to coexist with humans, and no vendor is more attuned to that than Apple. Its clients are renowned for their silent running, and Mac Pro, which has the same Core microarchitecture Xeon CPUs as Xserve, practically whispers. However, Apple’s first crack at an Intel x86 server isn’t everything that Intel’s “performance per watt” campaign might lead prospective Xserve buyers to expect. Xserve is not distinctly frugal in its power consumption. It generates as much heat as I’d expect from a two-socket Netburst Xeon server. And Xserve is noisy. There’s just no getting around that.

Measuring power consumption at minimum and maximum combined CPU and local hard drive load yielded measurements of 300 and 400 watts, respectively. The power supplies are capable of satisfying markedly higher power demand, creating a few hundred watts of headroom in my tested scenario. Power levels did not rise noticeably when two power supplies are installed, even though both supplies run constantly. However, Xserve exposes no user-definable power profiles; the Energy Saver preferences pane does not have a reduced speed setting. Xserve eats whatever it wants to. That’s typical among Intel x86 rack servers, but I had hoped for the ability to set the system’s maximum power level for those times when efficiency trumps performance. Xserve’s automatic power management is fairly aggressive, though. CPU core voltage drops quickly when demand falls. Apple’s administrative interface does not report the CPUs’ clock speed, but I assume that it shifts as core voltage does.

At one foot from the front panel, Xserve’s sound pressure level registered a fairly steady 60 dBA, and around back, 65 dBA. This is not an acoustic breakthrough when compared to the PowerPC-driven Xserve G5 or to two-socket Netburst Xeon servers. EPA guidelines set 80 dBA as the danger threshold for workers without hearing protection, so a single Xserve’s fan noise falls well within the safe range. Even so, it highlights the importance of protecting your hearing in the server room. If you can’t have a conversation without shouting, your environment is dangerously loud.

The new Xserve does not share a key quality with Xserve G5: The fan noise is not decreased by disabling one of the CPUs. Xserve G5 gets markedly quieter, but then, the PowerPC 970 CPU has more on-board peripherals. Shutting down a socket took bus drivers with it, while Intel’s x86 busses are all external.

Xserve’s exterior thermal profile strikes me as mostly average for a modern Intel x86 1U rack server. At the back panel, I measured peak temperatures of 118 degrees F, while the front panel ran only a few degrees above room temperature. The system’s forced-air cooling is very effective. I was troubled by one focused hot spot of 108 degrees on the top cover, at least ten degrees hotter than the average for that surface in a room at exactly 78 degrees. High radiated heat is potentially hazardous for the equipment in the space above the heated device. It’s harder for air conditioning to remove, and it’s usually symptomatic of inadequate heat sinking. That may be something that Apple will address in a future design. However, the toaster on Xserve’s system board, Intel’s Core microarchitecture north bridge (front-side bus controller) chip, isn’t something that Apple can easily chill. It runs as much as 60 degrees Fahrenheit hotter than the CPUs. In fact, it’s hotter by a wide margin than any other component according to Apple’s sensor data. Apple can convert this from radiated heat to forced-air heat, but its burden on power and cooling will remain.

Thank you and goodnight

I have referred throughout this story to the plethora of sensors inside Xserve. One of the delights of OS X Server is the simple, yet deep management and monitoring tools that come with it. Sensors and tools are not new to Apple. What is new is that sensor reports and management tools now operate whether the system’s power is on or not, and whether you’re on the same subnet as the server’s Ethernet ports or not. The magic is lights-out management, long a feature demanded by Intel x86 server buyers but absent in Apple servers. Now, Apple has equipped Xserve with a standards-based baseboard management controller that operates continuously as long as AC power is available. The BMC draws negligible power when Xserve is off, making it very UPS-friendly, and you can reboot, power down and power up Xserve from anywhere. These operations previously required that OS X boot successfully, but an OS that won’t boot is a pretty common reason for an administrator’s Blackberry to buzz.

Xserve’s lights-out management is powered by Intel, and it implements version 2.0 of the IPMI (intelligent platform management interface) specification. That doesn’t mean much right now, because even though IPMI is a published specification, that spec is so impossibly convoluted that the only effective IPMI consoles are those created by OEMs, and these are closely guarded intellectual property. An open source project, openipmi, aims to change that, and remote management hardware maker Cyclades (now part of Avocent) has announced its plan to open its IPMI software development kit. In the meantime, Apple’s only IPMI-equipped software is the Server Monitor GUI. I was not able to use Server Monitor to target Xserve remotely, and pointing Server Monitor at Xserve’s lights-out IP address returned nothing (although that address did respond to pings). I have no doubt that this will evolve quickly, but Xserve users may want to keep polite pressure on Apple to make sure that on-board monitoring and logging facilities are accessible from local and remote text connections as well as the command line.

An objective reviewer’s job is to find fault, and I’ve done my job. But the sum of Xserve’s flaws is overwhelmed by the system’s unique leading-edge, user and administrator-centric engineering. Xserve is far better than the commodity server that the Intel x86 market expects. But what really blasts Apple’s competition is OS X Server. The present Tiger (10.4) release is more than a match for much more expensive commercial Linux, and far more capable out of the box than Windows 2003 Server. Early next year, OS X Server Leopard (10.5) will transform Apple’s already industry-leading Xserve, including the model reviewed here, into an unimaginably feature-rich native 64-bit server platform. And guess what? When you buy it, you’re done paying for it, and all of the services you have to buy, build or rent with Windows, Linux or pay-as-you-go service outsourcing, are installed on every Xserve’s boot drive. Call me old fashioned, but I prefer Xserve’s buy once, run forever approach.