Catalina - External Hard Drives repeatedly ejected without cause.

Hello PeterRobin1,

Thanks for visiting Apple Support Communities,

I understand that your external hard discs are ejecting at random. The following guide detailing how to reset the System Management Controller should be helpful:

How to reset the System Management Controller (SMC) on your Mac

Best regards.

It is discouraging. :(

Is this how you went back to Mojave?

Do you have a Time Machine backup to Restore to/from?

https://support.apple.com/guide/mac-help/revert-to-a-previous-macos-version-mh15216/mac

Anyone want to give this a go and report back? Preventing spotlight from indexing the external drive...

I found this old apple discussion with the same issue on Yosemite with a confirmed solution. https://discussions.apple.com/thread/6607988

1. Connect the volume or drive you want excluded to your Mac.

2. Open the System Preferences application.

3. Click on Spotlight, then click on the Privacy tab.

4. Drag your volume or drive into the Privacy menu to exclude them from Spotlight's indexing.

I've got this problem too. It happened suddenly, and has been an issue with multiple drives. Being a longstanding Mac user, I've encountered this before. It usually happens with USB 3 drives, usually when connected through a hub. As far as I've been able to figure out, it's to do with macOS being unable to adapt to having a USB 3 drive operating at lower bandwidth, which happens when you connect a drive (or multiple drives) through a hub, or when multiple devices are connected to the same bus. The best solution is a direct connection and to make sure they don't share the same bus (just because you have 4 thunderbolt ports, doesn't mean internally they are each separate. On the Mac Mini 2018, for example, the two on the right are connected to one bus, while the two on the left and the USB 3 ports are on another bus.) Another solution that always seems to work is to put a USB 2 cable joiner between the USB 3 drive and where it is plugged in, effectively, this turns it into a USB 2 drive. It slows the drive down, but it makes it more reliable, which can work well for backup or non-critical data drives where speed is less important. This is also a way of controlling which drives get more bandwith and reserving it for those that need it.

It's important to understand, it's not the drives that are faulty. This is a long standing issue that needs to be fixed. My other suggestion is to give Apple feedback on this through their feedback page or write to them directly, so they are more aware of the issue.

https://www.apple.com/feedback/

In Finder's Menu, select Go menu>Go to Folder, and go to "/volumes". (no quotes)

Volumes is where an alias to your hard drive ("/" at boot) is placed at startup, and where all the "mount points" for auxiliary drives are created for you to access them. This folder is normally hidden from view.

Drives with an extra 1 on the end have a side-effect of mounting a drive with the same name as the system already think exists. Try trashing the duplicates with a 1 or 2 if there are no real files in them, and reboot.

If it does contain data...

http://support.apple.com/kb/TS2474

This seems to be a very, very long saga: and, like others, I'm shocked that Apple has not addressed it successfully long ago.

My experience is this:

• there are random (panic) shutdowns any time I have either or both of my new LaCie 2big Thunderbolt3 drives connected
• this happens whether they are connected directly to the Mac, or via an OWC Thunderbolt 3 dock
• also true whether I am daisy-chaining to the LG 27" 5K monitor or using separate ports to the Mac
• this has been happening with my Mac mini (which has also, on Apple support's advice) had an SMC re-set (no difference) AND on a brand new MacBook Pro 16. - ie it really doesn't seem to be something to don with your machine folks

For the moment, I have connected the LaCie T3 drives using their USB connections (via the OWC T3 dock). It has run this way for about a week so far, with no recurrence of the kernel panic shutdowns.

Clearly, if I'd wanted a couple of USB drives in this set-up, I'd have done it more cheaply with other options - so I do want to go back to T3 connections as soon as possible. If the expected further update to Catalina 10.15.5 doesn't resolve the issue, I'll be applying to Apple for a refund on the LaCie drives.

Hi H-E-J,

As you might have read, I also suffered a random unmounting after installing the 10.15.5 update. For me, it turned out the hurdle to fixing the drive is the way macOS automatically kicks off a repair process without communicating this in any way via the graphical interface. It seems that when a drive is determined to require filesystem repairs, the OS silently initiates fsck_hfs (filesystem check for HFS+), which must run its course before the drive can be mounted. I killed off the fsck_hfs process using the Terminal and ran Disk Utility on the drive so that I could monitor the progress of the repair process. After many hours, the filesystem was repaired and the drive is working as expected. Fortunately, I suffered no data loss. If you are indeed encountering the same issue, I suppose you could just let the silently initiated fsck run until it fixes the filesystem damage that the update caused, but there is no feedback provided while it is running.

https://matthovey.wordpress.com/2013/06/17/resurrecting-a-time-machine/

Apple, this issue is the result of two organizational failures.

1. Please fix your QA process. Prioritize the quality of releases over their frequency. Catalina has been — by far — the buggiest macOS release I have used in years. The marketing people may crave a yearly release for their purposes, but it leads to technical debt and bugs that cause serious disruptions to users.
2. Provide a user-centered interface when the system determines that a drive needs filesystem repairs. Less technically inclined users need to know that their drive experienced some damage and that the system is attempting to fix it. Silently initiating a process that may require upwards of a dozen hours can leave people with the impression that the drive must be erased and reformatted.

I'm not much into installing betas either, but with all the stability issues and ongoing problems with Catalina, it seems to me that it's only a matter of time before the betas for Big Sur are better put together and more reliable than Catalina, which will probably only get a few more updates at best. To me, that makes installing the beta another option to downgrading to Mojave.

For me, the choices are:

• Stay on Catalina and put up with it for the next few months, until Big Sur is released and proven. This will cause a loss of productivity, due to ongoing issues that have already been mentioned earlier in this thread. In my case, the hard drive disconnects are only one of many issues. While my Macbook Pro works reasonably well other than being slow and laggy, my main machine has been rendered largely unusable due to kernal panics, hard drive disconnects, video playback at hyperspeed and various other Catalina issues, so remaining on this OS isn't much of an option.
• Go back to Mojave, and loose about a week of productivity due to having to set up multiple machines from scratch. This isn't much of an option either, when the new OS is around 6 to 8 weeks away, and I'm going to have to go through this process anyway, when upgrading to Big Sur (which I will make sure to do a clean install with).
• Upgrade to Big Sur, while it is still in beta. This isn't a good option either, due to the risk of software breaking and general issues encountered with betas. However, Big Sur looks to be a vast improvement in terms of general reliability, and it is actively being worked on, so the kinds of issues plaguing Catalina are far more likely to actually get fixed. In my view, if I'm going to encounter beta type issues with Catalina, I might as well go to an actual beta, and have the bonus of the issues being able to be reported and fixed.

I've been largely hanging in there, putting up with my main machine in its current state, using my laptop as much as possible, and even using an old iMac (running Mojave) and a ten year old Windows 10 machine for some tasks, but my patience is beginning to wear thin. Like many people, I use my computers for work and these issues have cost me a lot of time and lost productivity due to having to continually fix my machines.

One thing that might be worth trying, is with OnyX. In desperation, with two backup drives refusing to mount, and after one of my main data drives coming up as unformatted multiple times, being restored multiple times (six in total), and even being replaced and doing the same thing, but it did allow me to use the drives again. I ran the maintenance scripts in OnyX. I only discovered this after loosing the data on the data drive. I am slowly restoring this drive from the cloud, because on top of the random ejects and the drive coming up as unformatted multiple times, my Time Machine backup failed as well. It said it was backing up, but there were no files actually being saved! I have no idea why running those maintenance scripts worked, but I do know they clear a number of caches, so I am assuming that one of these must have got corrupted at some point. Here is a link to download OnyX: https://www.titanium-software.fr/en/onyx.html and a screenshot of the options that were selected. I didn't change any of these from the defaults as far as I'm aware.

Just received my brand New 2020 iMac 5k quite a have few external drives

1 x Drobo D8 Thunderbolt 3

1 x Drobo 5D3 Thunderbolt 3

1 x Drobo 5D USB 3

1 x Pegasus R6 Thunderbolt 2 with a adapter to Thunderbolt 3

1 x Drobo 5c USB 3 used as Time Machine back up

System installed from scratch no migration only essentials installed.

Energy Saver - Put HD to sleep disabled, Power nap disabled

Mountain installed - Prevent Unmount enabled

Still Mac goes to sleep and ejects and re-connects random drives mainly USB 3 and Thunder bolt 2 to Thunderbolt 3 drive

So damm Frustrating

I am having the exact same issue, Peter. I have gone through the same steps as you have and the issues continue. I am currently searching for other solutions. If you discover any please post them here, and I will do the same.

If the G Tech drive with just Thunderbolt proves to be trustworthy I would strongly suspect the power supply. Have you checked with G Tech to see if there is a firmware update that needs to be applied for Catalina compatability?