How to check that your Mac backup works
Many people only find out when restoring that the backup had not run for months or that files are missing. A test takes ten minutes and gives you certainty.
1. When did the last backup run?
For Time Machine the date is in System Settings › General › Time Machine. If it is more than a few days old although the Mac was on, something is wrong.
2. Restore a few files
Pick five to ten files from different folders: a document, a photo, a file from your mail folder. Restore them from the backup into a new folder, never over the originals. With Time Machine, open the folder in the Finder, choose “Browse Time Machine Backups” in the menu bar and go to an older state.
3. Compare byte for byte
Opening a file is not enough; a damaged file can still open. Compare checksums in Terminal:
shasum -a 256 ~/Documents/Contract.pdf ~/Desktop/Test/Contract.pdfIf both strings match, the file is identical. Important: the file must not have changed since the backup.
4. Check the stored data
For network backups Time Machine offers “Verify Backups” (Option and the Time Machine icon in the menu bar). With restic, restic check --read-data-subset=5% reads part of the stored data and reports damage.
5. Repeat regularly
A test is a snapshot in time. Put a monthly reminder in your calendar, or use a tool that runs such probes itself and shows you the result.
Lifeboat backs up your Mac with restic to a disk, a NAS or your cloud storage, and restores random files every week to show you the backup works. 14 days of everything free, then 1 disk free or Pro for €39 once.
See Lifeboat