Catalina - External Hard Drives repeatedly ejected without cause.

still not unmounted itself... happy SSD tb3 working with catalina.

Thank you for the link. This could be a lifesaver in terms of fixing this issue. Very much appreciated. I'll give this a try and see how it goes. :)

I've also had this issue except with USB (G-DRIVE 10TB USB-C connected to US) and surprisingly my thunderbolt harddrive hasn't had any issues

I don't blame you, but I fear the OS is headed the opposite direction you're hoping for.

yea don't really want my drives permanently spinning, apple needs to get their **** together

I thought it might be a diagnostic tool to help pinpoint the cause if nothing else.

yes mate it does, I also installed Mountain which supposedly prevents the drive from being ejected but even that does not work.

Interesting, thanks for the report.

Agreed. My drives are all Seagate USBs, not Thunderbolts. 2 full size 6GB, 1 portable 4GB.

Thanks....I'll give it a shot.

did not work for me unfortunately

Oh, I am so glad (well I guess not really... misery love company?) to see I am not the only one having this problem. I have posted about it elsewhere in these forums.

I updated to Catalina and random shutdowns ensued only when the Thunderbolt (1) drives I used for TM backups were mounted. Tried various fixes, clean install, fresh backups, many calls to Apple Support... eventually bringing the iMac into my Apple Service Provider, along with the external hard drives I used for backups, both of which were connected via the Thunderbolt 1 interface (one of them via a Thunderbolt to Firewire adapter). They rebuilt (as it were... cleaned up) the iMac Fusion Drive, redid the clean install, and tested both external hard drives, reformatting one of them (at some cost). They could find no hardware issues with the iMac.

Problem persisted with random shutdowns when external hard drives were mounted. So replaced both with new USB external drives... no more shutdowns. Griffin replaced the G-Drive Pro Thunderbolt along with a new Thunderbolt cable under warranty. I retired the other older WD drive (firewire connected via a Thunderbolt adapter). But problem persists.

Then I did another clean reinstall, migrating only User Data over (no Applications or Network Settings) to see if this would fix it. Problem persists only when the Griffin G-Drive Pro Thunderbolt is mounted, random crashes (shutdowns), not when the two USB external drives are mounted.

There is no Firmware update for the G-Drive that I could find (oh, and I reset the SMC and NVRAM... not the cable, but it has happened with two separate cables... could they both be bad?).

Apple says it must be a hardware issue since I've done all I can, but I have a feeling Catalina is not playing nice with the Thunderbolt interface or just the G drive architecture somehow. The problem only surfaced with Catalina.

Love to know if anyone else has gotten any info on this.

If anyone figures out a fix, I would love to know. Anytime I have the G-drive Pro Thunderbolt (Thunderbolt 1 in my case) connected, I can get random shutdowns. Never happens with just USB drives mounted. I have tried every fix known to Apple to no avail. After the last clean install, I was able to backup to the G-drive, left for a couple hours, came back and found the random shutdown had occurred. I tried clicking on the G-drive icon to see its contents. got a spinning beach ball and then the dreaded black screen. I finally emailed Griffin support. Love to get a fix... these drives are not inexpensive, and to have them basically unreliable with Catalina is just bizarre and frustrating.

I had upgraded my 500GB SSD to a 2TB in my trash can Mac Pro, just to be able to use the thing, as the OWC Raid volume kept disconnecting during use. I'm giving this Keep Drive Spinning utility a try, fingers crossed.

I’ve actually had great results from usb powered external drives over the years. In this case, my drive failures are with a powered tb2 external drive, and the Keep Drive Spinning utility seems to have helped so far, as I’ve had no disconnects since. The problem is clearly an Apple screwup, one which they apparently have determined is not in their interest to fix quickly. I’m happy to have a suitable 3rd party workaround to apple’s bug, but disappointed that Apple has so badly dropped the ball on a serious issue.