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Backing up with Apple’s Mac Backup
Apple has a built-in backup program that backs up to your account called, simply, . It requires a account, at $99/year ($69 if purchased with a Mac or iPhone).
Issues with Mac Backup
Mac Backup offers the ideal scenario of backing up critical data to another offsite location (eg Apple’s servers), but in actual use the program is a dismal failure, quite literally.
The first problem is that Mac Backup is unreliable, a non-starter in a backup program! More on that below.

Second, disk space available at
is too little to perform even a fractional backup of all my data. Adding more storage costs extra— and you have to pay every year. And believe it or not, 60GB is the maximum amount of storage you’re allowed to buy.For these two reasons, the Mac Backup approach as a whole can only be considered a toy, albeit one that some users might find works well for them, at least for a while. If the service did work reliably, I would be using it for certain critical data— but it just doesn’t work.
Even so, it’s a flawed strategy, knowing that when you hit 60.1GB, you’ve got to find another solution (actually much earlier than that, since some space is needed for mail and incremental backups).
Specific problems

In my experience, Mac Backup (used on Mac OS X 10.5.6-10.5.8) inevitably starts to fail, and once it fails the first time, it frequently fails most of the time, sometimes never succeeding ever again.
Deleting all prior backups from
seems to help, but that is likely just random luck.Fails, but no errors reported

After failure, Mac backup usually shows no error in its “details” (see below).
Sometimes it reports an error code -5000, which is “Insufficient access privileges for operation”.
Shown below are the details it provides when clicking the little red icon for details. This backup failed, yet one wouldn't know it from the details. The entire scan-and-fail process took 25 seconds.
Connected to .Mac Begin backup at 2009-08-07 11:52:12.359 -0700 Scanning files... Acquired a destination for the backup. End backup at 2009-08-07 11:52:37.547 -0700
POC
Shown below what I typically encounter with Mac Backup . It’s not reliable and therefore unusable, Apple needs to fix this piece of crap. I’ve given up on Mac Backup. You want perfection? Read magazine reviews.
A backup program has to work 100% of the time, which is why I prefer making critical ones manually (eg Finder copy). I know I can count on such backups: no buggy software to screw things up, no invented-by-dumb-asses proprietary file format— just plain old files I can get to at any time.

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