External Drives in Monterey

I have the identical problem; until I updated to Monterey, my Time Machine backups worked perfectly on my Seagate external 1T drive which is partitioned to two 500 GB, one for Time Machine, one for my disk backup with SuperDuper. First Aid in Disk Utility always fails. After I erase the TM partition in the Recovery Disk Utility, all works fine for a day, then the Time Machine partition stops mounting.

With so many others having this issue, it certainly seems like it's an Apple software issue. Such a time-consuming nuisance to have to keep going into Recovery to reformat the partition, to only have it work for a few days at most.

The 'Energy Saver Preference' approach may work for internal drives, but it certainly doesn't work for Ethernet-connected drives (which is how my TimeMachine is linked). Again, this wasn't an issue before Monterey, and doesn't appear to affect TM backups. It's just a nuisance that appears to be collateral damage with Monterey.

BPBear544 wrote:

The 'Energy Saver Preference' approach may work for internal drives, but it certainly doesn't work for Ethernet-connected drives (which is how my TimeMachine is linked). Again, this wasn't an issue before Monterey, and doesn't appear to affect TM backups. It's just a nuisance that appears to be collateral damage with Monterey.

Quite right, Bpbear, energy saver has no effect on networked drive, but then it wouldn't, as the whole point of energy saver is to reduce the power to spinning or otherwise attached drives. I don't have numbers, but I would imagine the energy consumed by your computer keeping a networked drive 'up' is negligible - though still a non-zero figure - even if that same drive is consuming power attached to a different computer.

In any case, as you say, it will not work for you, so it is a separate, albeit undoubtedly equally annoying, issue.

Lawrence is absolutely right though, we must ALL let apple know of these issues, so that by being aware they exist, they might, just might, try to fix them.

File those bug reports, and repeat for each iteration of OS12, or each computer, if you have several. The squeaky wheel gets oiled :)

I'm still having this issue.

Drives randomly are 'not available' or 'not mounted'.

Just found out today that all my backups (including Backblaze) are two days behind because of this.

Arq backups to a WD Red in an enclosure stopped because the drive was unmounted (but still appears in Disk Utility).

Arq backups from my RAIDed SSDs fail because the backup is unavailable, yet I've been working in folders on this drive from the command line for days.

Had zero problems with Big Sur, it's not hardware.

Kernel panics have subsided this week.

Reported to Apple.

Just letting people know, check your backups, etc.

2017 iMac Pro --> CalDigit TS3+ --> 2x Thunderbolt SSDs in RAID0
            +---> Sabrent HB-U93W --> multiple wall-wart powered USB drives

macOS 12.3 (21E230)

I actually misspoke above. The two SSDs are connected directly to the iMac Pro.

I've since removed the doc and the main USB backup drive is direct connected.

I shared a link to this thread with Apple support. Maybe something will come of it.

He had me reset SMC, so I gave it a shot.

so, I was working on my father's iphone 8 a few days ago, and connected it via usb cable to my 15" macbook pro (2015)

It kept mounting and dismounting, and charging seemed to be cycling, lasting only a second or two before cycling again.

I thought it was perhaps a dodgy cable, so of course tried another. Same same.

Thought then it must be the phone (bought s/hand) so tried my phone (8+), same same (I usually charge my phone via wireless charger, so hadn't noticed this issue before).

Then tried father's phone with first cable in my 2012 17" macbook pro, all hunky-dory and fine. My phone, hunky dory

After doing some googling, I found someone who recommended this command line prompt to try to resolve the issue, and it worked - it would then charge and remain mounted on the 15" 'book

sudo killall -STOP -c usbd

I wondered if this daemon might also be affecting the sd card slot reader, since it is also usb (internal), so I mounted the sd card on the 15".

That was 3 days ago, and it hasn't unmounted since. Could be unrelated and merely coincidental, serendipitous good fortune, but might be worth a try.

As usual, I recommend not trying with anything that has data that cannot be replaced.

Cheers!

I have noticed this issue on 2020 mac mini that i bought recently. It started disconnecting external drives randomly. I will have to reinsert them and mount back and run first aid by disk utility resolving issue. Still happening as of now. is there any resolution for the issue?

I had so much trouble with my Seagate external drive partitioned for Time Machine and SuperDuper backups unmounting after upgrading to Monterey (as well as other issues with Monterey), I went back to Catalina.

Now I'm having the same issue with inexplicable unmounting of the Seagate Time Machine partition with Catalina. I had absolutely no issues when I was running Mojave.

Often I have to go into Recovery Mode/Disk Utilities to reformat the drive. Not sure whether it's related to the Seagate brand, as I have other backup drives that are functioning fine under Catalina.

Same issue. My Seagate 1T external drive connected directly to my MacBook Air was partitioned to backup Time Machine and SuperDuper. This worked fine in Mojave. In Monterey the Time Machine partition kept unmounting. I could only reformat that partition to APFS by going into Recovery. Disk Utility on the local computer did not work. Finally erased my laptop hard drive and installed Catalina, and am still having the same issue. Time Machine backed up fine yesterday, today unmounted and I received the message the Time Machine could not backup to the disk. Disk Utility in Catalina formatted the TM partition in APFS, and now Time Machine is formatting it in Mac OS Extended to prepare it for backing up. I have no doubt I'll be facing the same issue tomorrow.

I have just acquired a new MacBook Pro running Monterey 12.3.1, and it is randomly unmounting and then remounting my Seagate portable drives. I stream video from these drives, and the streaming is also frequently freeze-framing as if the data flow is being interrupted. I cannot run a 45min video without the freeze occurring several times, and unmounting occurring two or even three times. This never happened with the previous machine (an older MB Pro running Mojave), and I see from this forum and other discussion sites that Monterey now has a reputation for this damaging activity. Is Apple ever likely to fix what is surely a bug in Monterey?

As this discussion clearly implies, this behavior is a problem with Monterey and solely with Monterey and external drives. As you say, it is potentially damaging and Apple should address it. But, of course, there is nothing but silence from Apple.

I am having the same issue with a MacBook Air with Catalina. My iMac with Catalina is not having issues, but I've erased the laptop, reinstalled the OS, also erased the Seagate backup drive, partitioned for an external backup as well as Time Machine. The unmounting issue keeps occurring. I'm wondering if it's the Seagate drive itself. As I keep my .dmg downloads in a Dropbox folder, I'm able to reinstall my apps without too much difficulty.

I am having exactly the same problem with my 2021 iMac 27" (Intel) running macOS 12.3.1 using every conceivable method of connecting my 8T external drive. And I 'never' put my Mac to sleep, so it's not a wakeup issue for me. It is definitely a Monterey problem that Apple should address, perhaps before counting their Mon(ter)ey. For now, I am using CCC and DSuperDuper! for reliable backups. 'They just work.'

A simple workaround is to not sleep the computer but just put the screen to sleep. What with SSDs they don't need to be put to sleep like rotational HDs do to extend life.

So, I ran disk first aid and rebuilt the disk directory and it seems to have fixed the problem, thanks for the tip!