External SSD only works when plugged into a USB hub, not directly into MacBook Air

Possibly of interest:

SanDisk Support – Your Portable SSD May Require a Firmware Update

"We have identified a firmware issue that can cause SanDisk Extreme Portable SSD V2, SanDisk Extreme Pro Portable SSD V2, and WD My Passport SSD products to unexpectedly disconnect from a computer."

The page has a place to enter the serial number of your SanDisk SSD to see if it is one of those affected.

dburke wrote:

I thought of that too, but it works even when the hub isn’t connected to any other power source.

Sometimes a hub is necessary. Some years ago I had to use a hub to connect my external USB3 drives to my Mac or the Mac's USB ports would be deactivated until I rebooted the Mac. It never deactivated the ports while using a hub.

Plus not all devices are fully compatible with all computers. In fact, I would be a bit leery of anything from Western Digital since WD is not always to be trusted.....SanDisk is owned by WD. Some stuff from WD is fine for a while, but later on that same item may not be fine. WD has been this way for decades.

If you are using an M-series laptop, did you approve allowing the SanDisk drive to connect? I don't know if using the hub could change that behavior. I personally use "Automatically when logged in" since many times I don't see the notice to accept or deny the connection.

If your Mac asks you to allow an accessory to connect - Apple Support

It’s an Anker 7-in-1. It can provide power through a USB PD input port, but the drive works just fine through the hub even when it’s not powered.

FYI, those power input ports on many docks, hubs, adapters are usually only to supply power to the laptop and will not actually supply power to the devices on that dock, hub, adapter.

dburke wrote:

That'd be a bummer. What if I didn't own a hub? The hub's USB-C speed is also a fair bit slower than the port and the drive support, so I'm losing almost half the write speed out of the gate in that case.

There should be no difference in speed if you use a proper hub to match the speed of your devices. If it is a USB3 device, then you definitely do not have to worry since the Mac's USB3 speeds are only half of what most hubs can handle. A Mac's USB3 maximum transfer rate is 10Gb/s even if your SSD is cable of 20Gb/s transfers.

Really? I hadn't heard that about WD. Who would you recommend?

@Servant of Cats' link is just one example of WD's deceptiveness. The information in that link should mention that firmware update is also to address data loss issues.

https://arstechnica.com/gadgets/2023/05/sandisk-extreme-ssds-keep-abruptly-failing-firmware-fix-for-only-some-promised/

I don't usually use pre-built consumer based external drives because many of them have one issue or another. I usually assemble mine from components I like & trust. However, OWC has been making Mac compatible devices for decades so they would be a good choice for you. I also like the Plugable brand devices, but they only have a very limited selection of products.

No matter which drive you select, you should always erase the whole physical drive because the manufacturer's can use some odd partition layouts & file system choices as well as placing secret items on the drive that can sometimes interfere the operating system's ability to access the drive. Apple doesn't make it easy to erase the physical drive because it is hidden by default in Disk Utility.

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Yep, I approved it. macOS even tries to read it, it just fails to.

Is this a standard data only drive, or is it a backup drive such as a Time Machine backup drive?

Are you using any third party software to manage this SanDisk drive?

This seems to be able to power things. Even when my Mac has been away from the hub, I've still charged my phone and watch through it.

Every device requires difference amounts of power. Surprisingly some SSDs may require more power than one would assume.

But an unpowered hub does other things as well. It changes how the devices are seen by the system in some small way. Plus the hub can act as a buffer between the device & computer.....this is why I needed to use a hub on one of my Macs to prevent the USB3 ports from becoming temporarily disabled when using external USB3 drives.

Is it a powered hub? If so, then the most likely reason is the SSD requires more power than the laptop can provide.

Sounds like your SSD is drawing too much current connected directly to your Mac but OK in your hub so I assume it is a powered hub? However, not sure why an SSD would not be able to be read directly connected to your Mac as they usually do not draw that much current.

dburke wrote:

Ooof yeah I saw about the firmware update, but I didn't realize how toxic of a reputation SanDisk SSDs had gotten. And I'd just ordered one of the Extremes to replace this one! That's one of the ones affected, but it has the firmware update. Looks like I'll be returning it. Too bad, cuz it was the cheapest I saw for those specs from a brand I recognize. I guess I know why now.

SanDisk is generally Ok, but WD tends to be bring them down. I've heard that SanDisk may be spun off from WD soon, so there may still be hope for SanDisk. I used to always use Hitachi hard drives....they were the most reliable brand out there in my experience, but WD acquired Hitachi. After some years Hitachi seems to finally have gotten rolled fully into WD so I no longer have faith in Hitachi which is a shame since there are only two other options....one which had a worse reputation than WD for many years.

I will use the SanDisk USB sticks since they are usually one of the more reliable brands out there and they make a couple of models that have faster write speeds than any other brand out there.