How do you backup?
A backup could be as simple as copying files manually from one media onto another. For example, you could just drag your entire user folder onto an external hard drive. Of course, this requires you to do something! The best backup strategies work without you having to think about them (much). So the best choice is usually to use some kind of backup software.
This is where this guide becomes decidedly Mac-centric. All the software I have experience with is either Mac-only software or I only have experience with the Mac version. For all you Windows or Linux users out there, sorry... you'll have to find your own software. Still, my descriptions of the following programs may be helpful to you in determining what features are important to you.
It is also important to understand that there is an entire constellation of backup software available for the Mac (somewhere over 100, I believe), and I'm only focusing on a few stars. You may not find any of these programs suitable for your personal tastes, in which case you'll need to spend some time exploring other options. One good reference would be the online appendices of Joe Kissell's Take Control of Mac OS X Backups (which is also an excellent guide to Mac backups).
That said, let's get into my list of software. You can either read through the whole document, or jump straight to the software that interests you using the menu below.
Time Machine is Apple's backup software included in Mac OS X 10.5 (also called Leopard). Time Machine is designed to do automatic, frequent backups onto some kind of hard drive. It could be a hard drive attached to your computer by USB or firewire, or it could be something called a NAS (Network-Attached Storage) device. Apple even sells their own network device called a Time Capsule, which is a combined wireless base station and NAS drive designed specifically to work with Time Machine.
Time Machine does incremental backups and keeps every version of a file that it can. You can use the Time Machine interface to restore files from a specific date/time, and if your hard drive dies, you can restore everything from the Mac OS X installer. By default, Time Machine backs up everything, on every drive in or attached to your machine, but you can set it to exclude specific folders or even entire volumes.
Time Machine is designed to fill the backup hard drive completely, given enough time. Once the hard drive fills up, Time Machine will begin removing the oldest versions of your files from the backup in order to make room for newer versions. Thus, the larger the hard drive you use for your Time Machine backups, the more history you can maintain. This also means that Time Machine needs the backup drive to have a minimum capacity of 2-3 times the size of the source.
Unfortunately, this space-filling aspect of Time Machine means that it doesn't play well with others. If you're considering storing other data on the same volume as your Time Machine backups, don't... it won't end well. If your drive is ridiculously large for the data being backed up, you can partition the drive into two or more volumes and use only one of those volumes for the Time Machine backup. However, remember one of the rules from the previous section... don't store something on one partition and rely on Time Machine backing it up to the other partition. If the drive dies, both copies will be lost!
Time Machine does have some quirks, however. The backup storage appears, on first glance, to be a simple hierarchy of files and folders that matches (to some extent) the structure of the source. However, if you try messing with the backup (which you shouldn't!), you'll discover that there are some funky permissions on all the files. Also, some of the files are actually a kind of link to a file in another location in the backup, which means you will probably have difficulty if your machine dies and you need to access the backup, but you only have a Windows or Linux machine left. Time Machine backups can only be accessed by Time Machine, which means only from a Mac running Mac OS X 10.5.x or later. Note that people have lost their entire set of backups just by moving files on the backup using the Finder!
Multiple backups can also be an issue. Time Machine is designed to backup to one hard drive. Although you can swap hard drives regularly using the Change Disk button in the Time Machine preferences, this does make it a manual task. Swapping disks is a manual task already, but anything that helps to make it as automated as possible is helpful, and Time Machine is a bit lacking there.
Despite these issues, I do use Time Machine as one of my backups, since it requires almost no effort to use. (For someone who has a desktop machine, and doesn't have to remember to plug in the backup drive when your laptop's on the desk like I do, it can truly become no effort.) Since a couple of important attributes of a good backup are effortless backups and keeping multiple versions of your files, I would recommend Time Machine as a part of your overall backup strategy.
My recommendation: use Time Machine, but as with any backup software, consider using an additional utility for a secondary set of backups.
Backup is an older backup program from Apple, and is only available as part of a MobileMe (formerly .Mac) subscription. The primary use for Backup is to save backups to your MobileMe account, although it can also be used to back up to other media, such as a hard drive.
Using Backup to copy data on a regular schedule onto your MobileMe iDisk is a great way to achieve off-site backups. Unfortunately, your iDisk cannot match the available storage of online services designed specifically around backups. At the time of this writing (July 2009), you have a grand total of 20 GB of storage associated with your MobileMe account, and that storage must be shared between your MobileMe e-mail and your iDisk. Fortunately, you can set how much is allocated to each of these, but the most you can allocate to your iDisk is 19.97 GB (which leaves 30 MB for your e-mail).
If this amount of space is adequate for you, Backup in conjunction with a MobileMe account can be a very good part of your overall backup strategy. I have about 25 GB of data that absolutely must be backed up. While I could choose to back up just a part of that data to MobileMe, I can't put it all up there. So Backup + MobileMe is not a viable backup solution for me.
For a while, I used Backup to back up onto a pair of external hard drives, which I swapped between home and a safe-deposit box at the bank. However, I became uncomfortable with this, as Backup stores data in a set of proprietary files. With the advent of Time Machine, I was uncertain about the future of Backup. I did not want to rely on a backup solution that meant I could only access my backups with one specific program, whose future is uncertain.
My recommendation: if you can use Backup in conjunction with an iDisk, do so as a part of your backup strategy, but do not make this your only backup. If you want to back up to anything other than an iDisk, there are other, better tools.
Carbon Copy Cloner, from Bombich Software, is a free utility made for creating clones, as its name would suggest. CCC is capable of making a complete, bootable clone of your hard drive, but it can also clone only specific files and folders. It is extremely flexible, with the capability to do full backups every time or incremental, and to keep only the most recent versions of all your files or keep older versions in time-stamped folders. It can store each backup in a separate disk image (though I don't generally recommend storing backups in disk images, since a small amount of corruption destroys the entire disk image). Best of all, CCC does not store the backups in a proprietary file format (unless you ask it to use disk images). The files are simply copied, and are thus usable without relying on any special software. They do not suffer from the usability problems caused by odd permissions and hard links in Time Machine backups.
My computer is a laptop, which has posed problems for me in the past with backups. Backup, for example, required that I remember to run the backups manually when I had my laptop on the desk and connected it to a backup drive. CCC forms a partial solution to this problem. CCC can run backups on a regular schedule, but it can also be set to run your backup automatically when you connect the backup drive. This means I can just put my laptop on my desk, plug in the hard drive and let the backup go, without having to take the additional time to open up some program and tell it to start the backup.
Time Machine does the same thing, but where CCC has the edge is with support for multiple backup drives. CCC can be set to identify the backup drive by name only, so that you can have two or more backup drives with the same name and they will be used interchangeably. You can use one backup drive today and a different one tomorrow and don't need to do anything to make the switch. This means that maintaining multiple backups with CCC is a trivial task. I have two drives that I use with CCC: one sits in my desk, one in a safe-deposit box at the bank. I use the one at home for a couple weeks, then I take it to the bank and swap them. I don't have to do anything special to swap them... I just plug in the other drive and CCC figures out what needs to be backed up and what doesn't.
My recommendation: CCC is a truly excellent backup utility. CCC is free, though the author does accept donations. I would encourage you to donate if you find it as useful as I do, but there is no requirement that you do so. Although I always recommend using two different backup utilities to maintain two or more separate backups, if you really must use only one, CCC would be a good choice.
It has been a long time since I have used Retrospect - which was the mid-1990s - but it was very good software back then. At that time, I was in charge of an installed base of 50+ Macs at a university hospital. Some of the machines belonged to physicians, some to lab techs, some to secretaries, some to administrators. One of the tasks I had to do was figure out how to back everyone up.
We had the entire range of user ability levels, from the guy who spent money like water and was extremely knowledgeable about a wide range of hardware and software to the girl who was confused about why she couldn't drag the annoying "Macintosh HD" thing off the desktop into the trash. (I don't mean to stereotype, that's just the way it was.) So the backup had to fit the needs of all these people.
Retrospect fit our needs very nicely. I set up a Mac server with a tape drive and installed the Retrospect Remote software on all 50+ machines. The Retrospect software ran on the server, and every night backed up the contents of the Documents folder on all those machines over the university's ethernet network to the tape drive. All I ever had to do was change tapes. (And restart the server when some other process crashed it... ahh, the days before Mac OS X!) Best of all, the only thing all the end-users needed to know was that anything they put in the Documents folder would be backed up. This was, interestingly, the only flaw in the system... getting some of the less tech-savvy folks to put things in the Documents folder was difficult at times. It's important to understand, though, that this limitation was imposed by our lack of resources to back up the same system and apps from 50+ machines, and not by any limitation in Retrospect.
My recommendation: although I haven't used Retrospect in over a decade, and thus can't vouch for its current quality, it warrants a look if you need to set up automated backups of multiple machines to one central server. (You might also want to encourage users of each individual machine to perform their own secondary backups, both as an additional safety measure and as a convenience in case they lose data and need it restored quicker than you can get around to it.) If you just need to back up one machine, choose a cheaper solution.