Mac OS X Leopard - ARCAism

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CHAPTER 7 BACKUP, SYNCHRONIZATION, AND RECOVERY OF DATA
backup is a backup with an archive. In this case, when you back up disk A to disk B, the old
information on disk B will be moved into an archive, not deleted, which is particularly useful
since you can go back in time and recover files that have been previously deleted from disk A. If
you are more of a visual thinker, these differences are illustrated in Figure 7-1.
Figure 7-1. Differences between backups and synchronization
Generally, when you want to keep an extra copy of your important data in case something
happens to your primary data store, then what you want is a backup. When you have two data
stores that you need to keep current with each other, then what you want is synchronization.
Either way, you are creating a redundancy that is important should one data source fail. One
important note, though: creating a backup with archiving is the only way to effectively protect
against file corruption. If you synchronize or simply back up a corrupted file, then you are just
creating a new copy of a corrupted file, often overwriting an old, noncorrupted file.
Backing Up Your Data with Time Machine
Leopard introduces what seems to be a fantastic little backup utility called Time Machine. Time
Machine provides data backups of all your information complete with a historical archive of
data. The best thing about this, though, is that Time Machine does all of its work automatically
in the background, making it painless. The disadvantage, though, is that in order to use Time
Machine, you will need an extra hard drive connected to your computer for Time Machine to
back up data to.