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).