When you see a message saying Time Machine is full, read it carefully. A message like the one below does not mean your backups stop or you must replace the drive. It simply means you won’t be able to restore files that you deleted before the date shown.
Time Machine makes hourly snapshots of your files by copying them to a backup drive. This process continues until the backup drive is full. At that point Time Machine makes more room by removing old data from it – starting with files you deleted long ago. The date of your earliest backup can be found in the Time Machine application or its System Preference. You cannot travel back in time and recover files you deleted before that date.
Even when Time Machine cleans out old backups, it always retains backups of all files currently on your main (source) drive. And of course, it never touches your source drive(s).
Here’s an example. Suppose you created two files 5 years ago: a business document and a letter. About 4 years ago, you deleted the letter and last year you made changes to the business document.
Fast-forward to today. Over time, perhaps your backup drive filled and Time Machine had to remove backups from 3 years ago. You can no longer recover the letter – it was already deleted before the earliest remaining backup. But since Time Machine still has snapshots from the last 3 years you can restore either version of the business document. And if your main drive crashed or your computer were stolen, you’d be able to restore everything currently on your Mac. That’s the power of Time Machine.
In rare cases, Time Machine may tell you the files on your source drive(s) exceed the capacity of the backup. When this happens, you may need to change settings in Time Machine's System Preference panel by excluding some items from the backup. Or purchase a larger backup drive.
Examining the Time Machine drive
Open the Time Machine backup drive and you’ll see a Backups folder. Inside are folders for your Mac and each date/time a backup was run. While you can sort through the contents manually, some folders may be inaccessible. That’s why it’s best to use the Time Machine app (in the dock or menu bar) to restore files.
Manually deleting items from the Time Machine backup
Time Machine is meant to be automatic, and you can’t change or delete items from backups in the normal way. There is a special technique for removing particular items from the backup drive to make room for new files.
- Have a folder or drive you no longer want to back up? First, exclude it from the backup.
- Open the folder on your main drive that contains (or once contained) the original items.
- Click the Time Machine icon in the dock or in the upper-right corner of the screen.
- Optional: If the items are no longer present on your source drive, go back in time to a date when they still appeared.
- Select the items to delete from the backup in Time Machine.
- Click the gear button and choose Delete All Time Machine Backups.
- Click Cancel to close Time Machine. The items are still deleted.
Remember: it’s not usually necessary to manually delete items from the backup drive. Time Machine will remove old backups automatically when necessary.
