In the innocent days of the very late 20th century there was The Family Computer. This single computer sat in a home’s communal space and was shared by each of that home’s residents. For many of us, those days are long past. As computers have become more affordable, portable and necessary, it’s now common to find multiple Macs scattered throughout a home.

And because it is, it’s just as likely that some of those Macs have been retired, replaced with faster or lighter models. When that happens the question of what to do with an old Mac invariably arises. Given a multi-Mac household and the need to retain the data stored on those Macs, one of the first things you should consider is turning that old Mac into a backup server, one Mac to rule the backup roost. Doing so isn’t an overly expensive proposition and it’s relatively easy to set up, run and maintain.

Why a backup server?

Ask Apple about multi-Mac backups and you’ll likely be directed to its Time Capsule wireless hard drive. Time Capsule is an acceptable and easy-to-use solution as it allows you to back up multiple Macs running Leopard or Snow Leopard to a single device via Apple's Time Machine. However, if some of your Macs are using an older version of the Mac OS, you’re out of luck as they don’t support Time Machine. Additionally, if you have a lot of data to back up, the 1 or 2TB of storage found on a Time Capsule may not be enough. And of course you’re paying for features beyond storage, including wireless routing.

A Mac-based backup server allows you to get around these limitations. With the right software you can back up not only Macs running older versions of the Mac OS, but Windows PCs and Linux computers as well. You can add exactly as much storage as you need (and upgrade that storage at a later time). And you pay only for backup software and storage rather than a wireless router that may be redundant given the gear you already own.

About your setup

One reason an old Mac is ideal for this kind of work is because it needn’t be a powerhouse. Most of today’s Mac backup software runs on either PowerPC and Intel processors, requires that the Mac have no more than 1GB of RAM and much of it runs on older versions of the Mac OS (Roxio’s Retrospect 8, however, requires OS X 10.5 or later and 2GB of RAM).

Ideally, the Mac you designate as your backup server isn’t a power hungry beast (think Power Mac G5). A first generation or second generation Mac mini or MacBook is a good candidate in this regard because it doesn’t require a lot of power. Regardless of which Mac you choose as your backup server, create a schedule within the Energy Saver system preference so that it’s on/awake when it needs to back up your other computers and off or asleep when it’s idle.

The backup server and all the Macs you wish to be backed up will have to be on the same network. For the fastest backups, use a wired Ethernet network (preferably gigabit Ethernet). If that’s not possible, use a wireless network and be prepared to leave your Macs on for an extended period of time while they’re backed up.

Alternatively, if you have many Macs with a lot of data, are anxious to get this over with, but you’re unwilling to wire your home, it might be worth your while to drag all your Macs into the same room as the backup server and perform the initial backup over a wired network (or bring your Mac server to each client computer). Once that’s complete, return the computers to their original locations and perform subsequent incremental backups over your wireless network. Those incremental backups won't take nearly so long.

In regard to storage, hard drives are today’s easiest way to store backups. Storing backups on CD or DVD is fine if you have little data and a single Mac to back up, but it’s more trouble than it’s worth to babysit a multiple-Mac backup using optical media. Unless you have a Mac with an easily upgradable hard drive (an old Mac Pro or Power Mac G5, for example) you’ll want to get an external hard drive.

Next, calculate the amount of storage you need to back up all your computers and then double or even triple it. Thanks to massive media files and libraries, we store a lot of data these days. Unless cloud storage really takes hold we can expect to store increasing amounts of data in the future. While a 1TB drive may seem impossible to fill today, next year it may prove to be positively cramped.