I have a four year old M1-based iMac. Last year I bought a Seagate 4TB external disk for use as a backup drive for the iMac and for my wife’s MacBook, both with Time Machine. I followed advice from Take Control of Backing Up Your Mac, and have it formatted as APFS with two volumes, one for local backup and the other for network use.
The drive was randomly ejecting, and eventually was appearing to fail, so I got it replaced under warranty. Now the new drive is doing the same. I have a new drive, new cable, and have tried switching USB ports on the iMac, but it keeps happening. Sometimes more than once a day, but sometimes not at all for a couple of days or so.
I updated to Tahoe, and that has not made any appreciable difference. The only common factors left are the iMac and the setup for Time Machine use. I have two other drives plugged in, a 2TB Seagate disk for local backup and a 1TB Samsung SSD for making duplicates via SuperDuper! Neither has show this sort of issue.
I assume these are bus-powered drives. How are they connected? I assume you don’t have enough USB ports for them to all be connected directly to the computer. Make sure any hubs are powered and can deliver full power to every port that will have a connected drive.
Sometimes even powered hubs don’t have enough power to go around. For example, a 10-power USB 3 hub can theoretically provide 900 mA to each port (plus more for any ports that support power delivery). That’s 9A (45W) if all 10 ports are drawing the maximum. Adding a bit of overhead for the hub’s own use, you will need at least a 50W power supply to ensure that everything is sufficiently powered.
Many hubs (especially cheaper ones) will include a power supply that isn’t big enough to deliver full power to every port - if you exceed the supply, bus-powered devices will start getting flaky. Also, some hubs only provide power to some, not all, of the ports.
Power issues was one of my thoughts. I have four USB/Thunderbolt ports on the iMac, and no hub. I’ve tried both the USB 3.1 and USB 3.0 ports, with no change.
Possibly the cable itself could be an issue. From what I’ve read over the last year, ‘drives randomly ejecting’ has been a somewhat common external drive issue, and happening both with APFS and HFS+ formatting, and SSDs and spinning disks. The fix in a bunch of cases seems to be using really high quality cables..
Until recently I was using a OWC Thunderblade SSD externally powered and connected directly to my Studio as one of my externals, but it’s proved unreliable with the supplied TB cable. Spotlight indexing would cause it to immediately eject. Turning off the indexing fixed that. Then I discovered any large file transfers, whether as a Finder copy or with CCC- would eventually cause disk ejection after several hundred GB’s.
I’m currently contemplating either selling the unit or getting the pricey Apple TB cable and trying that.
In contrast, my other external 2 bay hotswap Thunderbolt unit with spinning disks has been bullet proof. I may test it’s cable with the OWC unit to see if that actually makes a difference..
OK, I have swapped in another cable, and we’ll see what happens. There don’t seem to be a lot of choices with the USB 3.x Micro-B connector for the disk, so I have a USB-A to USB-C adaptor (two different ones, both of which I have tried).
If it still happens, I would trying disconnecting the other Seagate drive or the Samsung and see what happens as one of those could be pulling more power and causing an issue when your 4TB drive is being used.
After swapping a cable, it ejected overnight. I had tried unplugging the 2TB Seagate drive, but that didn’t help. I will try disconnecting both that and the 1TB Samsung SSD.
If disconnecting drives is the only solution, then I am left with the problem of having to remember to connect disks when I do backups, which inevitably leads to missed backups and likely data loss. So I’d rather avoid that if possible.
Would I be better off with a different disk, perhaps from a different manufacturer or a smaller drive? I can’t justify the expense of a large SSD for backup at this point. Could it be a problem with the iMac?
I had this problem with my Mac Mini M4 dropping the connection to the network Time Machine drive that was physically connected to it. I changed the cable with no result. Finally upgraded the thunderbolt dock to an Anker Thunderbolt version five, which seems to have solved the problem.
Just looked at the Anker dock. €400 is a lot to spend on something that may or may not help! So I’ll keep it in mind, but look for other solutions in the meantime.
I have the 2TB Seagate and the 1TB Samsung SSD disconnected, and so far, so good. I’ll check back in tomorrow, most likely.
Alas, disconnected some time overnight or this morning, as the only peripheral connected.
As far as I can tell, this disk is not working well with my iMac. It’s the second disk of the same type (4TB Seagate Expansion external disk), and I have tried different cables and different ports. So one option is to try a powered hub, though that would be expensive, not to mention hard to source here in Finland. Another is to abandon trying to get it to work and look for a different option, though I don’t know what that would be — a different manufacturer, smaller disk, SSD disk? Possibly a third option would be to reformat it with just the one partition to handle the network backup from my wife’s MacBook, though 4TB is overkill for that, and there is no guarantee that it would work better that way.
How long are the USB cables you have tried? I mention because I was intermittently seeing “Disk Not Ejected Properly” when using a 2 metre cable, fixed by changing to an otherwise identical 1m cable. (In my case, USB-C connectors at both ends and USB 3.2 gen 2, but the length advice probably applies in your situation also.)
Exactly what drive is it? Is it a 2.5” drive or a 3.5” drive? I’m ssuming it’s the smaller, because it’s apparently supposed to be bus powered. Regardless, I do not trust Seagate externals even a tiny bit. The enclosures for the ones we’ve had here have been prone to fail, and can’t be taken apart without damaging them. I also don’t see any benefit to formatting what is probably a 5400 rpm drive APFS.
I have two M1 Macs here, a Mini and a Studio. Neither one supplies enough power to the ports to allow several drives to be connected and usable. I use a TB hub with a beefy power supply with the Mini. With the Studio, I use one of those OWC enclosures that holds both a hard drive and an SSD, and has powered TB ports.
All store-bought external HDDs are overpriced and underpowered. Which is why I always recommend buying an internal drive and an enclosure separately. So you can get good quality and if something fails, you can swap it without discarding both.
WRT APFS on a HDD, it works fine for backups (clones and Time Machine), where performance is not critical and snapshots are really useful. But for general file storage, you’re absolutely right - use HFS+ with HDDs.
FWIW, my external storage devices (all backup devices) are 4 TB Toshiba NAS-type HDDs (7200 RPM, rated for 24x7 operation), which I’ve mounted in separately-purchased enclosures. Each enclosure has its own separate power brick, with the data going over bog-standard USB 3.0 cables to a USB 3.0 hub. Works just fine for what I need.
We got a few of the older Seagate externals years ago when the Other Human was reviewing stuff. I ended up extracting all but one of them from their crummy enclosures as they began to behave erratically. I put them in spare OWC enclosures. My bus-powered external drives are almost all attached to powered USB hubs. They were bare drives that I installed in various enclosures, cheap and no so cheap. I’ve found some brands I trust more than others.
I tried deleting one of the volumes from the drive, but that had no effect.
So, from the comments about Seagate drives above (mine is 2.5” bus-powered), it looks as though power is the likely problem. Powered hubs just aren’t available from the Finnish retail stores (Power and Gigantti), so it looks like a special order from somewhere.