Time Machine drive causing my MBP (2021 M1) to constantly restart

I guess I should contact Apple Support about this. Recently I was trying to help a friend with his Time Machine drive that wouldn’t connect to anything anymore - his iPad, my old 2013 MBP, my MBP M1, etc. Whenever I tried, the computer in question would just repeatedly restart.

I put it off to the drive going bad.

This morning I woke up to see my MBP M1 (2021), which I usually never turn off, was not in a ready state. And all attempts to start it up caused repeated restarts. On a hunch, remembering the issue with my friend’s Time Machine drive, I disconnected my 5 TB WD Time Machine drive and voila - my MBP started up just fine.

I can’t imagine a way of fixing the drive though if connecting it causes repeated restarts.

Anybody else ever see anything like that? My CCC drive is working just find - same hub.


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Did you reformat the WD drive for Time Machine? If not it might be a WD “utility” doing unwanted things.
Otherwise it doesn’t sound too hopeful for that drive.
BTW the advice from Take Control books is to have morethan one TM drive. The Time Machine app happily swaps between available drives when doing regular backups.

Yes. I’ve been using this drive since 2021. I’m going to try to connect it to my 2013 MBP just to see if it connects. I wouldn’t mind reformatting it if that would help.

It’s working again!

I didn’t want to set my 2021 MBP M1 into a restart loop, so I tested with my 2013 MBP. I connected it and after some time was able to see it in Disk Utility. I clicked mount. It asked me for my password, and mounted!

So I tried the same thing on my MBP M1. It took a bit of time, but it also mounted. On my MBP M1 it didn’t ask me for my password for some reason.

Then it started the backup process and successfully finished! I look forward to seeing what it’s like in the morning. (And Happy New Year 2024)


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A few days ago there were problems again with the Mac restarting overnight. I immediately assumed it was Time Machine and unplugged and all was fine since then.

Yesterday I decided the Time Machine drive was just getting too “cluttered” and thus taking too long to do simple hourly backups. So I erased it and reformatted it as unencrypted (to save a bit of time). I set backups to manual to be careful.

The first one took a bit a of time but finished ok. And I just did another manual backup this morning and while it found over 1 million changes overnight and 8 GB of data to backup, it was quick and went well.

Later today I’ll set it to hourly again and see how it goes.

Maybe it’s a good idea every year or two to just start Time Machine over from scratch, assuming you have other backups and repositories.

I’ve always tried to do this.

I buy my TM drives a bit tight, that is, usually only ~ twice the size of the volume they’re intended to back up. That way I buy middle of the road capacity drives which renders best bang for buck, and, at the same time, it also ensures I end up having to start using a new TM drive about every other year — assuming I don’t want to see TM do any capacity-based thinning I generally consider a TM drive full and thus spent when it’s reached ~80% of its capacity.

So every other year or so I end up buying a new TM drive (well, actually, more like two since I have a TM backup disk I connect to at work and a separate TM backup disk I connect to at home). When I’ve filled up a TM drive, I switch to using the new drive. The old drive of course stays in a closet close by so if I ever need to copy something that’s older I can always easily and quickly find it.

This ensures you buy TM storage in a cost-effective way and that your TM is always backing up to a fairly ‘fresh’ backup, both in terms of disk itself as well as in terms of amount of co-existing snapshots that TM has to manage on that particular disk.

This has been working very well for me and I have yet to suffer any major TM trouble or find myself unable to restore from a TM backup important files from a specific date range. I highly suggest such a strategy to anybody using TM. In addition, of course, to relying on a 2nd independent archival/versioning strategy (in my case SD clones at regular intervals and always before major updates).

As mentioned in previous discussions Time Machine happily backs up to more than one drive, alternating between connected drives. My main TM drive is an external hard disk that is always mounted. Every few days I connect one SSD drive that I keep at home and a second SSD that I keep in the car. I usually select “Backup Now” from the menu bar but, if I forget, the SSD is automatically used by TM.
After major macOS updates I usually update a Carbon Copy clone as well.
Over the decades I have replaced my main TM drive a few times. I must admit I don’t know if the old drives (in a crate in the cellar!) will mount and be readable. Same with a stack of CDs and DVDs that I used before Time Machine. I even have some ancient Zip drives that I successfully mounted using a Zip reader purchased via Amazon. But I digress…