Time Machine is the breakthrough automatic backup that’s built right into Mac OS X. It keeps an up-to-date copy of everything on your Mac – digital photos, music, movies, TV shows and documents. Now, if you ever have the need, you can easily go back in time to recover anything. Set it, then forget it.
To start using Time Machine, all you have to do is connect an external drive (sold separately) to your Mac. You’re asked if you want it to be your backup drive and if you say yes, Time Machine takes care of everything else. Automatically. In the background. You’ll never have to worry about backing up again.
Time Machine backs up your system files, applications, accounts, preferences, music, photos, movies and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of every file, it remembers how your system looked on a given day – so you can revisit your Mac as it appeared in the past.
Enter the Time Machine browser in search of your long-lost files and you see exactly how your computer looked on the dates you’re browsing. Select a specific date, let Time Machine find your most recent changes or do a Spotlight search to find exactly what you’re looking for. Use Quick Look to verify the file’s contents if you wish. Then click Restore and Time Machine brings it back to the present. Time Machine restores individual files, complete folders, iPhoto libraries and Address Book contacts. You can even use Time Machine to restore your entire computer if need be.
How Time Machine works
Beneath the hood, Time Machine is every bit as remarkable as it is on the outside. It’s based on stable and secure Mac OS X core technologies (like the HFS+ file system), automatically tracks file changes and is aware of file system permissions and user access privileges. Bottom line: It’s working with more information than other backup utilities and doesn’t need to bother you for input.
You can designate just about any HFS+ formatted FireWire or USB drive connected to a Mac as a Time Machine backup drive. Time Machine can also back up to another Mac running Leopard with Personal File Sharing, Leopard Server or Xsan storage devices.
The moment you choose a Time Machine drive, a single folder is created on the drive. Inside this folder is a subfolder for each Mac being backed up. (Yes, multiple Mac systems can share the same backup drive.) And within each subfolder is another list of folders – one for every backup performed on that Mac. Time Machine uses a standard file system to store all of its information. Nothing hidden anywhere.
The first backup
For the initial backup, Time Machine copies the entire contents of the computer to your backup drive. It copies every file exactly (without compression), skipping caches and other files that aren’t required to restore your Mac to its original state. Following the initial backup, Time Machine makes only incremental backups – copying just the files that have changed since the previous backup. Time Machine creates links to any unchanged files, so when you travel back in time you see the entire contents of your Mac on a given day.
Every hour, every day, an incremental backup of your Mac is made automatically as long as your backup drive is attached to your Mac. Time Machine saves the Time Machine iconhourly backups for the past 24 hours, daily backups for the past month and weekly backups for everything older than a month. Only files created and then deleted before the next hourly backup will not be included in the long term.
Say Time Machine is in the middle of a backup and you want to shut down your Mac or put it to sleep. Who wins? Like you have to ask. Time Machine simply stops the backup process and remembers where it is. It automatically resumes when your Mac is active again.
Adjust your backup
By default, Time Machine backs up everything on your Mac. But if you want to exclude certain files, that’s easy enough. Just go to Time Machine preferences and check Time Machine backup window “Skip system files” or specify folders you wish to skip. You can also delete a single file or folder that you’ve been backing up – and delete it from all of your backups going back in time.
One day, no matter how large your backup drive is, it will run out of space. And Time Machine has an action plan. It alerts you that it will start deleting previous backups, oldest first. Before it deletes any backup, Time Machine copies files that might be needed to fully restore your disk for every remaining backup. (Moral of the story: The larger the drive, the farther back in time you can back up.)