Dual power supply options made the Xserve very robust, even the Mac Pro can’t compete, despite Apple’s claims

The demise of the Apple Xserve has been a cause for concern for the growing number of businesses with a commitment to Mac OS X. Apple claims that a desktop Mac can be used instead. But even the most powerful desktop Mac isn’t rack- mountable and doesn’t have redundant power supplies, so doesn’t tick the boxes required for industrial-strength servers.

Many users will still need the key features of the Xserve, so we’ve taken a look at the alternatives. For many years, users in the publishing industry have been successfully using Unix-based servers for communities of Macs and PCs. For an alternative to OS X Server, the extended version of OS X that Xserve runs, Unix is an obvious solution. After all, OS X is a type of Unix, and runs on the same processors.

There are lots of services offered by Apple OS X Server, but most are replicated by Open Source solutions in Unix. Apache, which OS X uses as a web server, is available on Unix. Most other services, such as DNS, DHCP Server and LDAP Authentication Services are available as Open Source. However, these don’t always match all features found in OS X Server and commercial software may be needed for full feature matching.

Any Mac user can turn on File Sharing in System Preferences and share files with other users on the network. This is an easy way to share files, but not particularly secure or fast. It also means users need to manually keep track of versions of files. File servers manage access to files centrally, thus avoiding any confusion with versions of a document.

Hardware alternatives
Typical file servers will include lots of memory, storage and fast multicore processors. RAID storage is a common feature, which is fast and resistant to disk failure. Likewise, an additional backup power supply, which kicks in if the main one fails, makes the server very resistant to disaster. Normal desktop Macs don’t have this sort of robustness. So while they might cope well with day-to-day tasks like email or print serving, they may not be suitable for tasks like file serving, where users work on live documents held on the server.

Apple offers the Mac mini for lightweight server duties, but it’s not up to the job of a busy file server

A typical Xserve with Dual Xeon processors, 12GB of RAM, 1.5TB of RAID-controlled storage and a redundant power supply costs around £6,500. A comparable PC server configured to the same specifications comes to less than £4,000. However, to completely replicate the Xserve functions, you need to budget for software.

Sadly, Apple doesn’t allow users to run OS X Server on non-Apple hardware. However OS X is derivative of the Unix operating system, of which Linux is a free open source version. From an architectural viewpoint then, replicating Xserve functionality on a non-Apple computer is better aligned to Unix than Windows, unless there are significant numbers of Windows clients on the network.

The fact that OS X Server has the same Graphical User Interface (GUI) as OS X makes it compelling to systems administrators not trained in IT – and this accounts for a large proportion of existing Xserve users.

Although there are generic GUIs for Unix, these are not the same as OS X and can be confusing for non-Unix users. A more acceptable option is to provide an OS X application that runs on any OS X client and allows remote configuration of the server. Helios uses this method, meaning an OS X user can configure the Unix server running Helios remotely, without knowing anything about Unix, or even seeing it.

A Windows-based server instead of a Mac OS X or Unix-based server may look like a compelling choice. However, Windows stopped supporting the Apple Filing Protocol some years ago. An alternate strategy is for Macs to use native Windows services, since they are supported as part of the Mac OS. However, this has performance and functionality compromises.

Apple led the networking game early on, introducing plug-and-play networking with AppleTalk, which simply defined the rules for one Mac to talk to another. The sharing of files involved a file-sharing protocol called the Apple Filing Protocol or AFP.

File-sharing protocols are very important and they deal with several users attempting to access the same file simultaneously. Unix and Windows have their own file-sharing protocols, and each of those have variants and plug-ins to improve compatibility. These file-sharing protocols are slightly different and, generally, any mismatch of client and server native protocol results in some feature or performance compromise. For this reason, professional OS X applications mostly demand servers that support the AFP protocol.

Open source
Various open source implementations of AFP have been developed, the most significant of which is Netatalk. This runs under Unix/Linux. Mac users wanting to use open source software to share with Windows are stuck with Samba, which does the job, but has its drawbacks. Samba introduces inconsistencies with file-naming conventions that cause problems with mixed-platform environments. Strict file-naming conventions must be used to avoid problems.

There are commercial AFP solutions available, such as Helios, which publishers used long before Apple released any server hardware, way back in 1989. It is still widely used in newspaper production, and other mission-critical settings. Xinet also offers AFP services but with integrated asset management for Mac and Unix servers.

Effective alternative
Although the demise of Xserve means that loyal Apple customers need to look elsewhere for a server with the same capabilities, a machine running Unix offers a very similar experience with the right software.

With a host of open-source solutions, most services can be replicated on a Unix machine. For some more important services, like file sharing, or email, it is worth spending money saved on hardware on commercial software that offers less compromise on user interface and features. By doing this, a Unix server can be as simple to use as the Xserve was.