Monterey struggling with External SSD

I am also having this issue on a brand new 14" Macbook Pro running Monterey. At first I thought it was an Apple Silicon compatibility issue, but from the others here it sounds like it is an issue specifically with MacOS 12.0.1. All of these external SSDs worked perfectly with zero issues on my 2015 Macbook Pro i7 running Catalina that I traded in. Now they randomly eject themselves and slow to a crawl, causing my whole system to freeze up. I was about ready to return my new Macbook until I found this thread that seems to confirm that it is a software issue and not hardware. I really hope this is fixed with a software update ASAP.

Judy sorry but what you presenting is not helping. This is a Monterey software issue that needs to be resolved quickly. If I can format a drive instantly on Big Sur, but it hangs when I use Monterey.....its a no brainer. Please pass it along to Apple Engineering or give us feedback on the progress of a fix.

I have the same issue. I have a MacBook Pro and two Mac Minis. After upgrading the MacBook Pro and the Mac Mini I use to run our Zoom Room, I thought I was all set. Then I updated a second Mac Mini that I use as a media server. That one has two external SSDs: 1) Samsung 2TB EVO in an external enclosure, which mounts and works just fine and 2) a Micron 7.68TB SSD I use for video media.

The Samsung works fine. The Micron? Would not mount. So, I moved it to my brand new MacBook Pro (M1) and same result. Shows up in Drive Utility, but won't mount.

I tried erasing and formatting as a new APFS drive, which appeared to work. When I started copy a back-up media set back onto the drive, it disappeared and will no longer mount.

I love Apple... I really do, but every time a major OS upgrade happens, it creates problems with external media. Big Sur's main issue was with my Thunderbolt 3 Drobo. Took Apple a long time to fix that problem.

Oh, well... I guess I just won't use my 7.68TB SSD.

I have two Samsung T5 500GB external SSDs connected to a Mac mini (2018) via USB 3.1 (Gen 2).

I've experienced some of the same symptoms especially with regards to mount and unmounting external volumes. It seems that the Time Machine volume, in particular, takes a relatively long time to mount. This may be due to the fact that the Time Machine volume is encrypted. Once mounted the SSD seem to perform normally.

Regarding slow transfer rates, I noticed that some older USB keys (USB 2.0) are ridiculously slow and take a very long time to unmount.

- Pie Lover

Okay, further to my earlier post. I have now taken the OWC 480 SSD that I had in a Seagate Backup Plus Portable Drive enclosure and transferred it to another portable drive enclosure. It now works fine on Monterey. I also tried hooking it up to another USB 3.1 controller and a USB 3.0 controller and it worked fine on each of them. So this seems to be an incompatibility with particular drive controllers/chipsets.

One more thing I forgot to mention. When I put the drive that was in the enclosure I am now using for my OWC 480 SSD into the the Seagate Backup Plus Portable Drive enclosure, it worked under Monterey. This drive, however, is not an SSD. It's a spinning/mechanical drive. So the Seagate enclosure would not work with the SSD on Monterey, but it would work with a spinning drive. Strange, I know. But everything is working now.

Very helpful... can you provide a link to the external drive enclosure that works with Monterey?

As an update to what I have observed, I re-connected my Micron 7.68 enclosure back to my M1 MacBook Pro, was able to erase and re-format for APFS, and then copy close to 6TB of data over from another source. No disconnects or errors of any kind.

When connected to my (slightly) older Mac Mini (quad core i3), I was able to connect the drive, but could not erase or re-format. After re-formatting on the M1 MB Pro, I would start to copy files and it would disconnect with a few minutes; then, back to unable to erase, et al.

All machines running the current version of Monterey.

iMac 2017 here. Fusion drive 1tb.

install failed on internal drive (hang at first reboot). Forced power off and then it boots but there are issues with reported free space (finder says 76gb, but any attempt of copying files produces disk full error). Tried reindexing and first aid. No chance.

then I tried installing on external ssd connected via usb c.

tried 3 clean installs.

every time it installs, but booting takes 10 minutes (literally). After booted, any disk access (finder, disk utility, etc) essentially hangs for several seconds to minutes.

I should add that there is definitely nothing wrong with the hardware. The same usb c drive works perfectly when accessed from a catalina install.

now I am downgrading to Big Sur, which worked fine. Will try a clean install on the internal drive…

i have similar issues with boot up times going from 20 seconds to over 5

minutes now. I have i5 Mac with 16GB memory, 2017. I suspect its because I’m using an External SSD to boot from. Monterey took ages to install as well. Maybe Apple are getting ready to ditch intel based macs and 3rd Party SSD Hardware.

Ditto, all of the above on an iMac 2017.

I will add: the drive that does not work under Monterey is an SSD ADATA with USB-C connection. I have other (older) drives via USB-A that work fine (seemingly), both HD's and SSD. But the "problematic" drive works perfectly on the same machine if I boot in Big-Sur.

I also tried with a USB-C (on the drive side) to USB-A (on the iMac side) cable and the result is the same. There must be some incompatibility of Monterey with some newer controllers.

Will now downgrade and wait for better times to upgrade...

My respons to mfulat was about slow booting systems, not external SSDs that would not mount which is an entirely different problem.

That being said I don't see any of the usual suspects in your report.

However, here's some food for thought: unless you're using a true VPN tunnel, such as between you and your employer, school or bank's servers, they are useless from a privacy standpoint.  Read these two articles: Public VPN's are anything but private and Former Malware Distributor Kape Technologies Now Owns ExpressVPN, CyberGhost, Private Internet Access, Zenmate, and a Collection of VPN “Review” Websites. 

I don't see any of the usual suspects in the report. Are you booting from the internal drive or an external SSD? The read and write times are about what I get when booting from an external SSD.

If you have most of your data files on the internal 5400 rpm drive that could be why you're seeing slowing. But boot times are depending on the drive type the system is on.

I would remove all of the items from the System/Users & Groups/Login Items preference pane and see if there's any improvement in performance. If there is then add them back one at a time to see which one slows things down the most.

Same issues here with my 2017 iMac. I have been using a WD 1Tb external SSD connected to the back of the Mac as my boot drive as it is way faster than the built-in drive on the Mac. After “upgrading” to Monterey the drive is there in finder, but the Mac is back to booting off the internal drive. Selecting the external SSD as the boot does nothing. Disk Utility says the drive is locked and times out when trying to unlock it. All worked fine in Big Sur

Had some time to spare , so I’d thought give another go.

I got rid of some unwanted software and cleaned up files with lost

links also this time I installed the Samsung T5 SSD software and to my surprise it thinks the drive is disconnected although the disk utility does see it and Monterey is operating on in all be it very slowly. I’m inclined to conclude this a Monterey issue. I thinks it’s back to Big Sur when I get time.