Backing up my Mac starts with Time Machine. The beauty of Time Machine is the ease of setting it up, plus the ease of recovering a file, project, or entire hard drive should something go wrong.
Time Machine is a continuous backup application. It doesn't back up your files every second of the day, but it does back up your data while you're still working. Once you set it up, Time Machine works in the background. You probably won't even be aware that it's running.
Where to Store Time Machine Backups
You'll need a place for Time Machine to use as the destination for its backups. I recommend an external hard drive. This can be an NAS device, such as Apple's own Time Capsule, or a simple external hard drive connected directly to your Mac.
My preference is for an external hard drive that supports all three common interfaces (USB, FireWire, and eSATA). I like multiple interface support because I can use the external hard drive to restore not only to my current Mac, but to any Mac I may purchase in the future. Consider the plight of individuals backing up to a FireWire external drive and then having their Mac die. They get a great deal on a MacBook for a replacement, only to discover that it lacks a FireWire port, so they can't easily retrieve files from their backups. There are ways around this dilemma, but the easiest is to anticipate the problem and not be tied to a single interface.
Time Machine Backup Size
The size of the external hard drive dictates how many versions of your data Time Machine can store. The larger the hard drive, the further back in time you can go to restore data. Time Machine doesn't back up every file on your Mac. Some system files are ignored, and you can manually designate other files that Time Machine shouldn't back up. A good starting point for hard drive size is twice the Users data space on your Mac.
Size of User Space
To find the size of your user data space, open a Finder window.
- Navigate to /startup volume/ where 'startup volume' is the name of your boot disk.
- Right-click the 'Users' folder, and select 'Get Info' from the pop-up menu.
- The Get Info window will open.
- In the General category, you'll see the Size listed for the Users folder. Make note of this number.
- Close the Get Info window.
The size of the Users folder is the value you should double to come up with a starting point for the size of an external hard drive. Why double? Time Machine starts by making a full backup of your user data. That will leave half of the space available on your external for the incremental backups that Time Machine will perform. This should provide anywhere from 1 to 6 months of backup space, allowing you to go back in time to retrieve any file from the backup period. If you need a longer backup window, or you regularly work with very large files, you may need more storage space, but twice the Users data size is a good starting point.