Late to this thread, but I’ve also been seeing this on my Mojave iMac (2019). With both a portable USB 3 external and a USB 2 desktop hard drive. They never disconnect when the iMac is awake.
Switching off “Put hard disks to sleep when possible” fixed it.
I’ve read stories from many people who solved their problem with this.
I wonder if some drives/enclosures respond to the “go to sleep” command by actually disconnecting from USB altogether, instead of just going into a low power state. That would probably produce the observed symptoms and would also indicate a really bad design for the drive’s USB interface chip.
Maybe. But the same drive had no such issues when connected with my 2015 MacBook Pro. I used Migration Assistant to get my data over to this iMac.
Back again to update my findings. The electrical outlet “problem” turned out to be bogus (see above). The outlet was fine. I had rewired all 80 outlets and switches in my son’s home during a remodel and I tested each and every one. I even took one outlet apart to see if a wire was loose. The culprit was a 3-in-1 adapter that tripped the drive when I wiggled it. Solved.
On to my new findings. My 2TB Iomega USB 2.0 keeps dropping out. This was happening primarily during Sleep. I read the Apple tech note about the different Sleep modes and therein lies the issue, apparently.
The USB system is powered off for all modes except when you just let the machine “turn off” by itself. The mode is controlled by the settings is the System Energy Preferences. I have the “put the drive to sleep when possible” box checked and do not have the problem during the day time. My problem only occurs overnight when I close the lid or press the power button briefly.
I have a late '13 MBPr using Catalina 10.15.6 and i use PowerNap. My GTech 4Tb drive connects by Thunderbolt port and the 2TB Iomega connects by USB to TimeMachine. This is clearly not a Raid setup more even a virtual copy. Let’s just call this a redundant non-synced backup. Because of the drop-outs, my 2TB drive resumes its backups in the morning when I login. Oddly enough, I do not have to reconnect the drive. So the message is incorrect about the disconnection. Of course, PowerMap provides for Time Machine backup during the night and used the Thunderbolt connection.
I recommend reading the article because it discusses what happens at different times there will be power loss to devices and memory for each mode. The one event I do not want to happen is hibernation because of the limited space on my 256GB internal SSD and 18GB of memory. My MBP is only powered by battery when I leave the house.
I’m still fuzzy about certain aspects of Sleep.
I assume that when under battery power, hibernation will occur when a certain battery level is reached. This might occur during a power failure, or if you closed the lid and went to a meeting and didn’t reconnect to power in time.
The fuzzy part to me is what type of Sleep is used when chosen from the Apple menu bar or the “Cancel, Sleep, Restart, Shutdown” panel. My guess, for battery powered machines, is that you get hibernation if on battery power, or else “lid close” mode where memory is maintained until battery is need.
HTH. Mike
Edit: Adam asked that I edit this update and supply a link to the Apple Support Article I referenced above. After 2 hours of searching Safari history, I gave up. It was an Apple Support Article and I’m not making that up. Here’s an approximation of the Apple article - "https://mackeeper.com/blog/post/366-do-you-know-what-sleep-mode-is-the-best-for-your-mac/ ". If anyone finds the Apple version, I’d be happy to correct this update. M
I just discovered this thread. I have seen this issue, or at least similar for some time. I don’t recall if it started with Catalina, which I have run since about the second update, or not. My external drive is connected continuously and is used for Time Machine, although I only run TM manually. Infrequently when I wake up my iMac I will have a message that the drive had been incorrectly disconnected. However, the drive has been remounted! Nothing else seems to be amiss. This happens so infrequently that I have never spent any effort to try to figure it out. It never happens except when the system has been asleep. The iMac is a 27", Retina 5K, Late 2015, OS 10.15.6. The external drive is a Mercury Elite Pro (OWC), 2 TB, connected directly via USB3. The iMac is on 24/7.
I have the same error that an older WD Thunderbolt 2 harddrive disconnects when my MacBook Pro is sleeping. It is connected via an OWC Thunderbolt dock. To the same dock I have a 2.5" Seagate USB disk connected used for TM backup. That disk does not disconnect… So for me it is something related to the WD disk, the Thunderbolt connection or the Thunderbolt dock+adapter (Thunderbolt 3 to 2).
I used to have the issue that the entire computer restarted after sleep but a reset of the SMC helped with that case… I am thinking of trying it again + nvram reset to see if it can help with the disk issue…
Since my external drives are SSD drives, there is no reason whatsoever to put drives to sleep. The only mechanical drive I use is for Time Machine and should never but put to sleep, ever.
Earlier versions of Catalina had a known bug of popping the Drive Ejected Improperly error.
Apple fixed that bug and in 10.15.6 it is gone as far as I can tell.
There was a different bug trying to shut down or restart, the machine would not shut down due to the Apple Photos daemons that run in the background to keep Photos in sync with iCloud.
The error tells the user to quit Photos, but quitting Photos does not quit the daemons running in the background.
As an aside, I was using Jettison by St. Claire Software but the OS not dealing with the Photo daemons just made Jettison not work.
The latest version of Jettison (1.8) fixes the Photo Daemon issues, quits them properly on shut-down and they will restart automatically via the OS on re-boot.
I would periodically have a hard or ssd disconnect without known cause using Mojave on a MBP.
I just shifted to Catalina and a new MBP. so far, no disconnects.
David
I recently had a spate of disconnects and thought it might be related to my new iMac, but cured them by power-cycling the TB3 dock and disconnecting all Thunderbolt cables and blowing out connectors and sockets with compressed air (at least it appears to be cured).
The Questionable Thunderbolt chain contains a Cable Matters Thunderbolt 3 dock, a OWC Thunderbay 4 with four drives in JBOD mode, a TB3 <-> TB2 Apple adaptor, and a OWC Thunderbolt 2 Drive Dock.
Maybe Catalina is more sensitive to briefly intermittent connections?
The TB3 dock only has two USB 3 connections currently as I’ve recently had a 7 port hub failure on one of the charging ports which has been replaced by a 10 port hub with 5V 2.1A per port. The two connections are a OWC Blu Ray burner (on) and an ASUS Blu Ray burner (powered off).
I’ve had three disconnect events within a week, one causing a kernel panic. After each event, I had to manually check all connected local disks - twice for APFS disks as there seems to be a boot mount and a data mount now. These checks range from practically instantaneous for boot mounts to hours for the local Time Machine disk.
I also purchased a CalDigit Thunderbolt 3 dock to replace the Cable Matters unit in case this disconnection event occurs again - I’ve had issues with Thunderbolt docks overheating in the past cured by replacement of the dock (OWC’s Thunderbolt 2 dock comes to mind which was sorta replaced by a Sonnet Echo 15+ dock). This can be redeployed for my MacBook Pro 16 if the power-cycle of the Cable Matters TB3 dock proves to be efficacious.
I also had a spate of NAS disconnect failures which were eventually cured (I think) by replacing the ribbon ethernet cable (supposedly CAT7 cable from Amazon) with a Cable Matters thicker cable from the iMac to the Orbi RBS850 satellite. This was another problem which took about 60 diagnostic steps to identify changing everything from the mount protocol (SMB or AFP) to reconfigurations of the ethernet adaptor to reinstalling the running system.
The Thunderbay 4 is the result of drive dropouts when my primary was a 2017 iMac 5K from 3 USB 3 external hard drives which became two TB3 OWC Mercury Elite Pro units in JBOD and finally the TB3 Thunderbay 4 unit in JBOD. The enclosure change was made in an attempt to cure the disk dropout problem and simplify power and data cable routing and (possibly) increase speed.
All fingers and toes crossed - the disconnections appear to have stopped.
The long and the short of it is that all my disconnect issues seem to have been cured by replacing marginal cables with known good ones, and disconnecting all cables and blowing out plugs and sockets with compressed air (I use cans of Compu•cessory purchased God knows how long ago.) My problems may be of my own making - I do smoke in my office and smoke particles may infiltrate my low voltage electrical plugs and sockets.
Environment: macOS 10.15.6 Build 19G2021, 2020 iMac 5K, core-i9, AMD Radeon Pro 5700 XT 16 GB, 4 TB SSD, 10 gb ethernet, 128 GB (non-Apple).
Bad cables, especially USB 3 cables, seem to be definitely a thing. My most recent problem was an external SSD being continually ejected (with “drive improperly ejected” notifications) on a nearly constant basis, but I’ve seen issues going back a few years. I’ve had to discard both Cable Matters and OWC cables—I’m using Amazon Basics now, which I have not had to replace. Thinking back to 1984, I haven’t seen this number of cable issues since the earlier days of SCSI. I’m running Mojave or High Sierra on the 5 or 6 Macs on my local network so cannot speak to Catalina.
I love Thunderbolt 3’s bandwidth, but am not crazy about the USB-C connectors.
Whenever I rotate my iMac, it seems the TB3 drives disconnect - it seems like thinking stern thoughts about TB3 causes them to disconnect (at least momentarily).
I picked up some OWC TB3 stabilizer clips and will see if they help in this regard.
I have noticed this as well and trying to figure if it is the USB-C design or the particular cable. I am afraid of moving my iMac screen as I will get the “You forgot to dismount the drive before ejecting” error. I have a thunderbolt hub just to be able to plug a drive in safely.
I haven’t seen this but once after running Catalina for about 2 weeks hard drive and SSD connected.
David
Not sure if it is a trend or not…but my Catalina iMac with an OWC TB3 2.5 inch drive RAID disconnected from the iMac yesterday. Hasn’t happened before and the iMac has been on Catalina for months. I powered the RID off and on and it remounted.
Yeah, I’m not a big fan of putting so much data at the end of a Thunderbolt 3 connection - love the bandwidth, less than enthralled with the USB-C connector (which seems to disconnect if you think stern thoughts about it). I’d blow out the connector and plug with compressed air - especially if you smoke. Remember to blow out the plug also - it’s not really a male plug but is female inside the metal enclosure.
Who designed this thing, anyhow? Probably some USB guy as the USB plugs have always for some reason had female plugs. Maybe they want to put the flexing contacts of the connector on the cable so if it gives up the ghost it can be cheaply replaced?
I swear our devices get bored and decide to screw with us.
“Let’s throw Verne a kernel panic and watch him run around with his hair on fire.”
Forget what The Terminator and Elon said: this is the real danger of artificial intelligence …
Probably a good occasional idea. It’s only happened once and the iMac mostly is the file server in the back room although I do use it for Lightroom for the bigger screen and faster processor as well.
I have a MacBook Pro and am having issues with many disconnects of an external hard drive, due to very loose USB-C connections. When I insert the power cable and other USB-C dongles into my MacBook Pro13" 2017, they are very loose on all 4 ports. If I plug the same power cable and dongle into my sons iPad Pro 2020, it is not loose.
Is anyone else on here having these issues too, it seems that many are on this link - Are Your MacBook USB-C Ports Loose? - AppleToolBox
My question is, do you know if this issue has been fixed with the new MacBook Pros? Or is it an issue with all USB-C connections on any device?
What advice would you give for solving this issue for the long term?
I have a 2013 27" iMac that I upgraded to Catalina a few months ago. Now running 10.15.6. It recently started showing these external hard drive disconnect warnings. I believe this situation corrupted one of my WD external disks that I use for TM backups. I bought a new Segate drive to replace it. I run dual TM disks always plugged in (they are the kind with power from the wall, not from the USB port). I am considering disconnecting one of them to hold back as a master TM backup. Hopefully Apple will address this problem in a future MacOS update.
I was a Catalina Beta Tester from the first beta. I reported this problem of external drives popping errors that the drive had been disconnected improperly even though the drive remained connected.
I got these errors even while I was away from the computer, sometimes multiple times, showing up as notifications. Apparently, so did others, and it was fixed eventually.
So if you are still seeing it, I would suspect the cable.
I use JSAUX 6 inch long pigtail adapters to convert old-style USB to Thunderbolt. They are cheap enough that the adapter stays attached to the cable coming from the external device.
Really high quality, snug fit, strong strain relief.
Here’s the link on Amazon . . .
https://www.amazon.com/gp/product/B07L749R9R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1