– Go to Application folder > Utilities > Activity Monitor.
– Select the Disk Usage tab and find out the size of your hard drive.
– Plug the external hard drive (bigger than the target hard disk) into your Mac.
– Go to Application folder > Utilities > Disk Utility.
– Select the external hard drive on the left and then click the Erase tab.
– Make sure the format of this disk is Mac OS Extended (Journaled).
– Type in a name for your backup and press the Erase button to format this disk.
– Go to System Preferences (in the Apple menu) and click on Time Machine.
– Click on Select Backup Disk...
– Select the destination disk in the list and click on Use for Backup….
– Slide the Time machine slider to On.
So that’s it. Time Machine will automatically backup your target disk every hour, every day and every week as long as the destination drive is available. And the oldest backups will be deleted when your backup drive becomes full.
For more info about Mac app, please click here.
If there is any folder you don not want to backup, you can click on Options… at the bottom, select the items from the exclusion list (or click on + icon to add the target folder/file you wanna exclude), and click on Save, then Time machine will back up everything in the target hard drive except for those items.
Time Machine allows for restoration of files, folders, applications or an entire Mac, depending on your need. How to restore: turn on Time Machine, click on a specific date in the timeline on the right side of your Mac, view the contents on that date (using Finder’s Quick Look feature), select the items you wanna restore, and then click on the Restore button. Those items will be restored to the original location.