Time Machine fully backs up your computers data to your Time Machine selected hard drive.
As long as your Time Machine hard drive is connected it will do a backup every hour.
The backed up data from Time Machine is available for you to restore files / folders and if needed restore a full backup including system files.
This is fine if you're not in a hurry, restoring from a Time Machine could take many hours depending on the amount of data stored.
Regardless whether down time is an issue for you, we really recommend using Carbon Copy Cloner, as a second back up strategy.
This is to be used in conjunction with Time Machine.
We have had instances the past when Time Machine back up has failed to restore correctly when it was needed most.
Please remember, you can't have too many back ups.
Carbon Copy Cloner can create fully bootable backups, this means in an emergency the hard drive you use for your Carbon Copy Cloner backup can be selected as the startup drive. This allows you to continue working and giving you time to arrange for the Mac to be repaired when it's convenient for you.
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