The Time Machine Mechanic, or T2M2, is a free utility which I wrote when I was wrestling with a bug which still plagues macOS Sierra. After a few days of continuous running, my iMac stopped making regular automatic Time Machine backups, but nothing in macOS told me that anything had gone wrong.

T2M2 thus sets out to identify and help diagnose problems occurring with Time Machine backups. It does so by analysing the unified log, which seems to work well in all versions of macOS from Sierra to Catalina. It isn’t designed to diagnose problems which are preventing backups from occurring in the first place, though. If you’ve upgraded to Catalina and can’t get Time Machine to work at all, T2M2 isn’t going to provide any useful information; you’ll need to look at my free log browser Consolation 3 instead, which has a simple setting to view Time Machine entries in the log.

Some users have pointed out that one common situation in which T2M2 could be more helpful is when a backup volume is running out of free disk space. Here, it isn’t helped by a change in the log entries made in Catalina: whereas T2M2 does report free space on Mojave and earlier, because those figures are now omitted in Catalina, users are missing what T2M2 should make obvious.

This is addressed in T2M2 version 1.8.

When run in any version of macOS from Sierra onwards, it now checks free space on the backup volumes which are mounted at the time. Unfortunately, if you mount and unmount backup volumes intermittently, and a volume is unmounted when you click on the button to Check Time Machine, there’s no reliable way that the app can check that backup.

Rather than puzzle you by changing the colour of the ‘traffic light’ at the top of the window, T2M2 uses coloured emoji to warn you when free space is getting low:

• A red No Entry sign ⛔️ indicates there’s less than 10 GB free.
• A yellow Warning Triangle ⚠️ indicates there’s 10-50 GB free.
• A green Tick ✅ indicates there’s 50 GB or more of free space.

I hope that you find this helpful. I have also taken the opportunity to revise the Help book quite extensively, including full details of this addition.

T2M2 version 1.8 is now available from here: t2m218
from Downloads above, from its Product Page, and through its auto-update mechanism.

I know that some would also want T2M2 to provide advanced checking and repair of Time Machine backups. For the moment at least I don’t intend adding that, for which you should use the Time Machine app, tmutil, and disk repair tools such as Disk Utility, which are designed for that task.