There are lots of backup apps, but more important than the app is your backup plan and then does the application support it.
The simplest backup is just clone using something like
Carbon Copy Cloner or
Super Duper. In essence keeping two mirror images of your system. The problem with that is if a file becomes corrupted on the master and then you clone the master you have also cloned the corrupted file so now you have two corrupted copies and no reliable backup. Cloning also takes a lot of time.
Next step up the ladder is an incremental backup which backs up only the changed files. A lot faster than a full clone, but still subject to the same problem of overwriting a good file with a corrupted version and losing the value of the backup. There are a ton of apps that support this kind of backup.
The best backup is one that allows some kind of versioning. In other words you retain the last "n" versions of the file. Then if a file is corrupted in the most recent backup, you can go to an earlier backup and still recover. You may lose some data this way, but you don't lose all your data. To my knowledge there are three apps that support this
Retrospect,
Tri-Backup, and
Data Backup. These also happen to be among the higher priced solutions.
Another issue is do you want the backup compressed? Compression saves backup space at the expense of being somewhat more complicated to restore. If you use versioning, you probably want compression too.
Third issue is what media do you want to backup to: a hard drive, a server, CD/DVD, magnetic tape what? A hard drive is the fastest and most common usually offering the most capacity without changing media, but backup hard drives are as subject to failure as the hard drive you are backing up. Any backup app supports this kind of backup. CD/DVD next most common but even with a 4.7 GB DVD may take multiple disks and are relatively slow. CD-RW/DVD-RW take forever to erase and are even slower than CD-Rs and DVD-Rs. Not all apps directly support CD/DVD backup either. Magnetic tape is cheap, but the drives cost several hundred dollars and Retrospect is about the only app that supports tape. Odds are, like most of us, you will compromise between security and convenience and use another HD for backups. (As far as I am concerned a backup on another partition of the same drive is too risky to consider.)
To me, a critical backup feature is automation. Any backup solution that is not performed automatically will be forgotten occasionally and following Murphy's Law it will be forgotten at the worst possible time causing the maximum inconvenience and data loss.
Probably the most often overlooked thing in a backup plan is recovery. How are you going to recover a single file that gets corrupted and how are you going to recover in a disaster when the entire HD goes bad? I use a bootable external drive and back my files up to a folder on that drive. In the event of a disaster, I can boot from the external drive and use the copy of the backup application to restore my main drive, or for a single file, I just use the copy of the backup app on my main drive to recover the individual file from the external drive.
So when you are looking at backup applications, price should be your least consideration. The backup media you plan to use, automation, incremental file backups, versioning, cloning ability, and data restoration should be your first questions. I think you will find Retrospect Desktop, Tri-Backup, and Data Backup have the most features, as well as being the most expensive. One thing, if you plan to buy an external hard drive for backups you will often receive a free copy of an OEM version of Retrospect. It may not have all the features but it has the most critical features and the price is definitely "right."
But that is just my opinion.
