Xserve Xeon review Part 2: Beyond Intel

Look harder at the hardware

With that subheading, you expect me to drone on here about the intangible value of build quality, great software and other Apple platform goodness that transforms the same-old, same-old $1,500 to $2,500 Intel rack server into something worth $2,999. Buyers of Intel servers are accustomed to comparison shopping based on hardware specifications and price, so let’s stick with hardware. The Woodcrest rack server basics that I detailed in Part 1 are a given. Apple went its own way even in its engineering of those features required to qualify Xserve Xeon to compete in its class. But, except to appreciate that Apple hasn’t lost its touch for server engineering, Apple-ness doesn’t raise the worth of Xserve Xeon. The direct value that Apple adds to Intel’s standard Woodcrest system design is easy to see if you open yourself to the possibility that putting Intel chips in a server needn’t define the boundaries of a server’s capabilities.

SAS, SATA, and DVD-R DL

Server-attached storage has gotten a bad rap for so long that vendors usually assume that 1U rack servers will use networked or external storage. Many types of server deployments benefit from the simplicity and speed of local storage, and to that end, Apple designed Xserve Xeon with three bays that accept removable Apple Drive Modules. Unlike the Mac Pro workstation, which you can expand with raw SATA drives, Xserve Xeon requires that you buy drives from Apple that are pre-mounted in Drive Modules. Fortunately, Apple’s markup for Drive Modules is reasonable–lower than other storage and server vendors with which I’m familiar. With three 750 GB SATA drives, 2.25 TB of local storage, an Xserve Xeon might take on roles you wouldn’t ordinarily assign to a standalone server. A giant swath of local disk is a real boon for grid applications.

The value twist that Apple put on Xserve Xeon’s removable drives is that each of the drive bays will accept either a SATA or a Serial-Attached SCSI (SAS) Drive Module. These two busses share one backplane physically and, it seems, logically: My Xserve Xeon eval unit shipped with three SATA drives, but the system enumerates them in its hardware inventory as nodes on a tree of SAS/SCSI devices. This is a cozy arrangement; Xserve Xeon’s internal drives and Fibre Channel-connected Xserve RAID volumes are all connected to logical SCSI adapters.

If you’re willing to sacrifice speed for capacity, SATA is for you. If you can’t bear the thought of life without 15,000 RPM drives, go SAS. Boot from SAS and put SATA in the other two bays, boot SATA and have a screaming RAID 0 SAS stripe on bays 2 and 3, whatever you like. With that flexibility, it’s much easier to plan for the use of hard drives for backup and portable storage. That strategy is advanced by OS X Server’s standard GUI and command-line tools for doing file and folder-level archiving with compression, creating virtual disk images that have compression and/or encryption applied, and creating formatted disk images that are ready to burn to DVD. OS X Server Tiger reduces full-volume imaging and restoration to single operations.

When OS X Leopard ships early next year, Time Machine will make backup continuous and automatic. I’m not sure how Time Machine will operate with removable drives, but given that they’re built into Mac Pro and Xserve Xeon, I’m full of ideas.

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.

Theoretically. My Xserve Xeon review unit arrived loaded with a private post-release build of OS X Tiger Server (10.4.8). In that release, the Setup Assistant that runs on the system’s first boot asks for IP addresses to assign to lights-out management. This, I learned, requires some planning because I fiddled with it long past sunrise and never got it right for my LAN. I did manage to get Server Monitor running on Xserve Xeon to talk to its local LOM, and located there the option for reassigning the LOM’s IP addresses. I’ll have to come back to the LOM; miles to go and all that.

Impressive connections

Earlier, I said that a system should have as wide a variety of data transfer modes as possible. Apple nodded at this with Xserve Xeon’s versatile removable hard drives, but under the urging of throughput-hungry customers, Apple kept going. Its new server has a total of three FireWire ports: two that operate at 400 or 800 Mbps, and one that operates at 400 Mbps. There are two USB 2.0 ports as well, but external storage and digital media devices are at home on FireWire.

Servers are just at home on FireWire. A seldom-recognized benefit of Mac FireWire ports is their usefulness as dedicated point-to-point TCP/IP links. The FireWire port on Xserve Xeon’s front panel is certainly there for external media devices, but it’s also a means for a FireWire-equipped Mac or Windows PC to move data to and from the server, establish a speedy Remote Desktop link, string a dedicated line between servers for replication and fail-over, or do anything else that one can do over Ethernet.

Xserve Xeon has risers for two expansion cards, and Apple puts a curious spin on this, too. Both of the bus slots are 8-lane PCI Express, with room for one 9-inch card and one 6.6-inch card. However, the 6.6-inch slot can also accommodate a 133 MHz PCI-X card. PCI-X was the Xserve G5’s bus, and Apple didn’t want existing customers to add the cost of PCI Express replacements for PCI-X cards in perfect working order.

Lastly, Apple didn’t cheap out with the on-board graphics. Yes, Xserve Xeon is a server, but it’s also a Mac. The ATI X1300 Radeon GPU (graphics processing unit) is fast and it outputs to either DVI (LCD) or VGA. To save back panel space, Apple uses a nearly-invisible mini-DVI plug. Thoughtfully, Apple includes mini-DVI to SCSI and mini-DVI to DVI pigtails. It plugged straight into a 30-inch Cinema Display and displayed a maximum resolution of 1280×1024 at 32 bits. You wouldn’t play video games on Xserve Xeon, but it is Quartz Extreme compatible, meaning that all of Apple’s complex graphics functions, such as native PDF rendering, can be done directly on the GPU.