Big Sur Disconnecting My External HDD

Interesting!! I'm having the VERY same trouble except mine is with the iMac that I purchased in January 2021. I have two external drives connected to it, one for Time Machine backups and the other for my Lightroom editing program. Every morning they're disconnected - but not ejected. Then when I try to eject them, I get a force eject message. That's the only way to get them to connect again. But what I'm really ****** about is that I've spoken with 3 levels of Apple tech support, the latest being "senior level" and none of them have acted like they know of any sort of issue like mine! They must not look at their forum questions, right? So my Time Machine HD started grinding, yesterday, (bought it Feb 1,2021) and so I worried it was crashing. I decided to return it to Best Buy. While there, I talked to a geek with Geek Squad. I tell him my issues with my iMac disconnecting from my External drives. He's not surprised at all. He said, "Oh yeah. They're having a problem with Big Sur and external HD's. We just got another notice about it this morning." Really Apple??? Even when I asked if Big Sur might have a bug, they all played dumb! The senior level Apple tech, Brian, even made a copy of my whole computer to send to engineers to look at. Never once have they admitted it could be a Big Sur problem. Why is that? My guess, because they don't know how to fix the problem so they don't want to admit there is a problem. This is what I call a coverup! Meanwhile, what do we do? Maybe we need to buy an HP.

Hi every body. Just today installed Big Sur, actual version is 11.2.1.

I get same problem, Big Sur automatically disconnecting my external HDD seagate 5tb, every few minutes. I can not do nothing, no Time Machine, no files.

Yesterday on Catalina, everything was good, today I suffering with Big Sur...

Changed two cables, tried everything what I could find in that topic, nothing working!

Apple, what happens? What I must to do? I need my Time Machine and files!

MacBook Pro 13" 2018 512gb. Seagate STHP5000400 5tb, formated — 1tb for TM (macos extended journaled), 4tb for job files (macos extended journaled).

My issue is just a TB3 SSD which has been connected to my Mac mini since day 1. All of my other external drives (USB-3.1, USB 3.0, etc...) work just fine.

This started when I upgraded to Big Sur back in November. I've been searching for a fix since. I'm thinking it's all about the driver at this point, but Apple is the cause, no doubt about it. Big Sur made changes to the TB3 configuration, and this is the result. All of my external drives worked perfectly (or close to it) in Catalina.

My Mac mini is covered by applecare+, so my case is getting pushed to the engineering team (regular support was unable to help after a few hours on the phone). I'm collecting the logs they asked for. When/if anything comes of it, I will share.

On the other end, my G-Drive Mobile pro TB3 ssd is still under warranty, so they are looking at it from the their end.

I am not able to load the G-Drive Mobile firmware updater. I get that "will not work on this macOS version" error.

My disconnects began at BS 11.1 and I am now on 11.2.1(Mac Mini 2018) with more frequent disconnects than 11.1. The 12 TB G-Speed Studio R RAID 5 remains powered and does not reconnect itself.

I changed the power-saving settings and will be testing 24/7 for a week. I will report results on this forum/topic.

Following up on my post a week of testing the impact of changing Power Saving settings suggested by Washeki. Both Lightroom Classic and Photoshop were mounted along with several other programs like Outlook, iStatistica Pro, Chrome etc. There was just one disconnect in 7 days when before there would be 4 or 5 per day, with computer running 24 hours.

Latest. It seems when I connected the SSD to the Thunderbay 4 a few processes prevented making changes to the home folder, even when I logged into a maintenance admin account I have.

I killed all of the processes one at a time, the kernel ended up being the last one, so I just manually disconnected. When I reconnected, guess what... Yep, the random disconnects started up again (while connected to the Thunderbay 4).

This kind of throws a monkey in the power issue wrench, at least in my case. I'm going to do a Big Sur reinstall once more...

I just upgraded to Big Sur. Darn. All 4 external drives just ejected while I was copying things over from one to the other. Earlier, my MBP couldn't even recognize one of them. I'm terrified about what this means. If so many other people didn't have the same issue, I would assume it's my USB port... but this is really distressing. I always hesitate to upgrade. Now I am reminded why.

Any way to return to the previous version to be rid of Big Sur??

Thanks Grayhicks and to all other replies,

I've discovered that not allowing my M1 Mini to sleep seems to solve the problem too which is somewhat helpful.

In truth though it's a bit of duct-tape fix for what should be a premium product. It's guessing it's far from optimal from a disk wear and tear perspective, and it's a shame coming from a product that prides itself on its low environmental impact.

Common Apple, this is a fundamental flaw - you can do better than this!

Thanks, David. In case it helps anyone else - I had two 3.5" SATA 3.0 USB drives in separate StarTech enclosures. One was a 1TB Samsung drive, the other a 2TB Seagate. Playing around, and for reasons unknown, the Seagate drive works in one enclosure but not the other, slightly older one (in that one the the mac sees the enclosure but refuses to mount the drive) but the Samsung drive is unrecognisable in either. Having bought one new 4TB Seagate drive and a new enclosure, everything seems to be fine (with this and the older 2TB Seagate) - the issue is that I don't know how to get my music library off the drive that the mac doesn't see! I am not keeping the mac awake all the time anymore.

Same problem here. I switched my g-raid dual spinning drive setup from an old computer running Mojave to a 2021 imac running Big Sur and at least once per day my hard drives get disconnected without being ejected. The hard drives have also been thrashing for days, I assumed the thrashing was from spotlight indexing or a failing drive, but since I am seeing that other people are having the same problem, I wonder if this isn't a Big Sur issue. My drives are connected through a dongle to convert USB-C to thunderbolt port. I don't have a thunderbolt port on the imac (which a design decision by Apple that makes my life difficult at least once a week, but that's another thread).

Anyone contact Apple on this or figure out a way around this without reformatting? I have been having same issue since install of Big Sur. I had my external drive being backed up via cloud service which hasn’t seen drive in 30 days and will be deleted from cloud. I need this data on the drive and cannot risk reformatting.

Exactly the same experience and solution I tried. My drive is an older OWC 60Gb SSD using SATA to USB cable. Does not disconnect during drive activity, just randomly throughout the day with an overabundance of annoying notifications that I can't seem to exclude.

I've had the same issues and got so frustrated that I had to go back to Catalina... I could not afford to lose my data after my hard drive kept ejecting and possibly corrupting each time. They need to fix this asap... I'm staying on Catalina until that is corrected.

Since the OP is apparently on an intel Mac and so am I (suffering the same problem), it is unlikely to be rosetta. I also do not run any Adobe products and still have the issue. You might want to make a new posting that makes the rosetta and adobe parts prominent. It might get the issue more attention from others suffering the same.