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Monterey struggling with External SSD

I had meant to add this to another tread but can't now find it - not even in Safari History.. Basically since upgrading to Monterey my MacBook Pro can't connect correctly to external SSD.

This is the text I was going to add to other thread.

When I connect my Seagate Fast SSD Media 1Tb which has two partitions one APFS and the other Mac OS Extended Journaled, the OS Ext mounts instantly but the three containers of the APFS take for ever. When I finally managed to open a folder in and APFS container and tried to open it, it threw the Finder into a nervous breakdown which could not be Relaunched via Force Quit. Disconnecting the drive brought Finder back to life. I tried on another port on my MacBook Pro 2016 and tried a different cable but all to no avail.  Connected drive to iMac running Big Sur and all works fine.  I was tempted to reformat the Max OS Ext to APFS but will wait a while and no great urgency. 

Posted on Nov 1, 2021 3:28 PM

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Question marked as Top-ranking reply

Posted on Nov 21, 2021 8:46 AM

KRisseeuw wrote:

1. I had several issues with external USB drives, Disk Utility and Time Machine on a new MacBook Pro M1 Max with Monterey 12.0.1.

USB3-drives are not properly recognized. Time Machine does not work.
2. USB-C drive did not work with either Time Machine or Disk Utility (see below).

Today I purchased a new SanDisk with USB-C connection to make a proper Time Machine backup. The Disk mounted, but Time Machine did not work, nor could I erase the drive with Disk Utility. I tried everything I knew, called Apple Support, but nothing worked (safe mode didn't work).

Workaround: I could solve it by using a Mac Mini 2018 with USB-C-Port, running MacOS Big Sur. Here the external SSD could properly mount and erasing + partitioning worked within 30 seconds. After this treatment, the drive worked well with my new MacBook. Time Machine backups worked fine after that.

Deducting from this, I see that it is not a hardware issue as much as a software issue, affecting both Time Machine and Disk Utility. I am guessing it has to do with MacOS Monterey.

The workaround as highlighted above solved it for the moment.

How on earth is this marked “solved”? The issue — Monterey has hosed compatibility with many, but not all, USB-C external drives — persists, even for KRisseeuw.

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155 replies

Dec 7, 2021 6:33 AM in response to imref

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.

Dec 10, 2021 4:39 PM in response to mfromwestmount

I've seen posts that these problems may stem the firmware update delivered with Monterey for some Mac models. In my case, I also have a Mac mini (2018). For this model, the firmware did not change from Big Sur to Monterey.


Perhaps this is one reason why I've not come across issues with external drives. The other reason may be that I use Samsung SSDs (T5 500GB, USB 3.1 (Gen 2), Type-C) which seemingly have a high degree of compatibility.


One of the SSDs works well despite being connected via a USB 3.0 hub which is not recommended (presumably because of power issues).


- Pie Lover



Dec 10, 2021 6:02 PM in response to BlueberryLover

Not quite comparable because it is an iMac, but anyway here we go:



Hardware Overview:

  Model Name: iMac

  Model Identifier: iMac18,3

  Processor Name: Quad-Core Intel Core i5

  Processor Speed: 3.4 GHz

  Number of Processors: 1

  Total Number of Cores: 4

  L2 Cache (per Core): 256 KB

  L3 Cache: 6 MB

  Memory: 16 GB

System Firmware Version: 447.40.12.0.0

  SMC Version (system): 2.41f2


Dec 13, 2021 9:52 PM in response to ahaynes4

I have a Pluggable brand SSD Thunderbolt drive. I had to use Disk Utility to erase and partition the drive as APFS. When I did that, I was able to download and install Monterey onto the drive. I then used Time Machine to bring all my other files to the SSD. I then used Startup Disk in the System Preferences to choose the Pluggable drive as my boot drive. Since then, my 2017 iMac has been blazing fast (the internal drive is just a storage drive at this point).


As a side note, I tried to reindex the Fusion drive by going to Spotlight preferences, dragging the internal drive to the window to exclude it from indexing, and then deleted it to force the Spotlight to reindex the drive. I restarted the computer probably 4-5 times and it was really quick. But then, all of sudden, it went back to a startup time taking over 10 minutes. Something really, really funky going on with the software it would seem.


So, I'm glad the SSD drive is working out. My 2017 iMac is quite comparable in speeds now to a brand new 2020 Intel iMac with the external drive when working in Final Cut Pro.

Dec 14, 2021 6:18 AM in response to mfulat

I upgraded my 2017 iMac to the Monterey update last night. I had it configured to use an external SSD as the boot drive to improve the overall speed. Prior to the update, with the previous version of Monterey installed, it was taking 15 minutes or so to boot, now boot times have returned to what they were under Big Sur. In addition, all the graphics issues I was having (light mode text displaying in black) have resolved. So it does appear that this update addressed at least a few bugs.

Dec 14, 2021 6:07 PM in response to mfulat

I have installed (fresh install) Monterey 12.1 on an external SSD (SanDisk Extreme 1Tb).

It works.


BUT if I connect the other external SSD (even when Monterey has booted), the mount hangs.

FYI, the other SSD is an ADATA where I boot regularly BigSur (and from which I am writing this), so it is definitely not an hardware issue.


So, progress, I guess, but not success.



Dec 22, 2021 7:39 AM in response to richard3

Similar problem here.

After an update to Monterey, my external Samsung EVO 4TB couldn't mount on my MacMini. I couldn't see it with DiskUtil. My MacBookPro couldn't see it (Monterey also). Even a MBook Air of a colleague didn't see it (Big Sur).

I had to go to a shop to format it with a PC.

Then, I can now see it and format it. But it's not working with APFS of HFS+. It seems to work with exFAT.

Dec 24, 2021 3:12 AM in response to moondav

My external 2TB LaCie SSD slowed to a crawl after updating to Monterey. It then (I thought) failed. I sent it back to Seagate...... anyway, long story short..... The drive has returned, formatted to ExFat - and worked perfectly. I reformatted to APFS and it again slowed to a crawl (3 MB/s on Blackmagic) ...... I reformatted back to ExFat - note: this can take about 20-30 minutes - and now works perfectly again..... 500 MB/s on Blackmagic...... Dunno what the problem is - Apple or Seagate (or both) - but I hope this helps someone else....... Format as ExFat.

Dec 27, 2021 11:23 AM in response to moondav

I ran into this problem yesterday and spent quite a while troubleshooting and finding a fix for me.


In my case I had a pair of SanDisk SSDs formatted APFS and their R/W speeds plummeted to super slow speeds in Monterey. On older macOSs (specifically Mojave) it was still fine.


By reformatting the drives as APFS on Monterey this solved the issue. In my case it was not as big of a deal since these were clone drives. I initially did one ExFAT and that worked fine but I really wanted APFS for the drives and experimented and finally got over my issues.

Dec 30, 2021 2:31 AM in response to larryg69

I have similar issues with Monterey macOS 12.1 on late 2018 Mac Mini. I have two Samsung external SSDs (500GB on USB3 and 1TB on USB-C) connected , and a third external disk which is a LaCie 4TB (format Mac OS Extended Journaled). Experienced kernel panic a few times a day. Same problem in Safe Mode. Have also reset NVRAM or PRAM. Problem settles down after disconnecting external drives. Very frustrating.

Dec 30, 2021 4:49 AM in response to iMAC212524

I'm also using a Mac mini (2018) with Monterey 12.1. I have 2 external SSDs both Samsung T5 500 GB models. One is connected directly to a USB 3.1 (Gen 2) port with a Type C connector. The other is connected to a (StarTech) USB 3.0 hub, again using a USB Type C cable. Neither disk is encrypted and I haven't installed the Samsung supplied software. The drives are formatted as multi-volume APFS containers (including Time Machine backup volumes).


These drives have been very reliable over the past 2-3 years (with Mojave, Catalina, & Big Sur). I haven't experienced any of the recently reported external drive issues with either of these devices.


The only time I experienced an issue is when I disconnected one of the SSDs before it was properly unmounted (which lead to system crashes). If I recall correctly, I wasn't able to completely repair it with the Disk Utility and eventually had to erase and re-format.


Hope this helps.


- Pie Lover

Dec 30, 2021 1:09 PM in response to BlueberryLover

PieLover, frankly, I'm not sure this helps those who are experiencing issues. We've established — a long time ago — that not all drives and systems are affected, but some are. That 12.1 did not clear things up for those still experiencing problems with their external drives under Monterey is also well-known.


I was lucky — for the most part, my issues were resolved with 12.1. But others, sadly, are still facing problems.

Monterey struggling with External SSD

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