Whenever an iPhone is synchronised with iTunes, iTunes makes a backup of (most of) the iPhone’s data. You can view the iTunes’ backup history by going to Preferences > Devices.
iTunes maintains some kind of history for successive backups, but I have no idea of the underlying logic. You would imagine that three or four backups would be queued and older backups retired as new ones are made. But no, that doesn’t happen. Instead iTunes seems to purge its backup history on a schedule of its own devising — I’m guessing maybe daily, but I haven’t yet bothered to try and find out.
The problem is that when something goes screwy with your iPhone or iPod Touch (like erasing your contacts during a Google Mobile Sync…) and you fire up iTunes to restore it from a backup you now to be good, you can bet that the backup will have been purged. (more…)