Every so often, Apple rolls out a feature that could have been just for me. Apple's operating system install discs are now shipped as DVDs, but the Xserve G5 sitting behind me has only a CD reader. Apple not only made a DVD-ROM drive standard, but it now offers a DVD +/- RW, dual layer drive as an option. Who needs a DVD burner on a server? I've got an external drive connected to my Xserve G5 now, and I build my PC servers with burners as a matter of course. Every server should have as many modes of data transport as possible. There are times when sneakernet is the best or only way to get from point A to point B.
BIOS is dead, long live EFI and LOM
Every Intel-based Mac has shipped without a feature that's a core design necessity in nearly all Intel x86 client and server PCs: The IBM PC BIOS (basic input/output system). That doesn't make sense. After all, the BIOS is part of the PC standard. Why break that? Let me count the reasons. No, let's save time with a brief rundown on what EFI, the Extensible Firmware Interface, is.
EFI is an embedded programmable firmware subsystem developed by Intel. Intel publishes detailed specifications and reference code on its site, which makes the word "extensible" plausible enough. You could look at EFI as a little system and OS that boots before your big system's OS boots. EFI uses device drivers, written by vendors or contributed from the community, to locate, initialize and even interact with hardware through scripts. With drivers that give it the ability to access a system's hard drive and understand its file system structure, EFI can load and execute scripts from that drive. It can negotiate booting from the LAN, and Intel's EFI reference code includes an interactive EFI command shell that lets you do some rather unexciting exploring before Xserve Xeon (or any Intel Mac) boots. Apple took advantage of EFI's flexibility to make the Boot Camp Windows compatibility hack work, and in the run-up to Vista, Apple appears to be working on EFI to ease direct booting and installation of non-EFI-aware OSes. In short, BIOS bad, EFI good, and Apple made the right choice.
Elsewhere in firmware, Apple has come around to a new idea: If Xserve requires a successful full boot of OS X before Xserve can be managed remotely, then diagnosing and correcting a boot failure is a tough job. Enter lights-out management, which Apple abbreviates LOM. Lights-out management is enabled by an autonomous embedded system that responds to management queries and commands without the OS's involvement or users' knowledge. Apple's LOM implementation conforms to Intel's Intelligent Platform Management Interface (IPMI 2.0) specification, with the exception of serial over IP, which is the rerouting of the serial port through a LAN connection. As with other approaches to lights-out management, Xserve Xeon keeps an embedded processor running even when the main system is frozen, sleeping, powered down or unable to boot. That processor listens for IPMI traffic on both of Xserve Xeon's on-board Ethernet ports. It does this without interfering with the server's normal TCP/IP operation. No matter what's going on with your server or networks, if you can work out a physical path to one of Xserve Xeon's on-board Ethernet ports, you can interact with LOM.