External SSD won't mount/missing in DiskUtility, but appears in SystemProfiler--help!

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External SSD won't mount/missing in DiskUtility, but appears in SystemProfiler--help!

I have a Sandisk 1TB Extreme USB-C external SSD that I bought and filled with an important 900GB dataset on about 16 months ago. I have not used it since. I have probably updated my mac OS to several versions later on both of my macs since I put accessed/filled the drive.

Today, I finally got around to trying to make a backup copy of it and I discovered:

It won't mount on either of my macs---a newish MBP running OS 11.6 or an old mac running 10.13 (via the Sandisk's USB-C to USB adapter).

On both macs, the drive shows up with basic information in SystemProfiler under USB devices (pic attached), but the 'Media' section of this info is missing.

It does not appear on Disk Utility at all (view external drives is enabled).

sudo pkill -f fsck did nothing.

Could this be a formatting issue, esp. since I upgraded my OS a few

times since I used the drive? What more can I do? I really need the dataset on it.

Posted on May 29, 2022 4:41 PM

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Answer 1

May 29, 2022 7:54 PM in response to cataclysmic

are you using any of sandisk's preloaded software on the drive that is supposed to make it "mac ready"? if yes, that could be the cause of your issue. when you use software from just about any manufacturer for their storage device you run the risk of that same software not being compatible with macOS updates / upgrades. it can cause the software to stop working. at best this will cause you a headache. at worst it can render your data inaccessible. it is always best to use disk utility to erase and format a drive before use to remove any preloaded software.

if you are using such software, i think your options are somewhat limited.

you may want to contact sandisk and see if there is an update for their software.

alternatively, if you have a backup you can revert your macOS to the version that the drive was working on and transfer your data to another storage device and then erase and format the sandisk device before putting it back into service.

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Answer 2

Owl-53

Level 10

102,877 points

May 30, 2022 2:13 AM in response to cataclysmic

The only common piece of Hardware that may or may not be the cause is " via the Sandisk's USB-C to USB adapter "

Can that piece of hardware be replaced or use a substitute USB-C to USB-A Adapter

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Answer 3

Barney-15E

Level 10

122,186 points

May 30, 2022 5:38 AM in response to cataclysmic

Does Windows identify the Format?

Without other software, it wouldn’t be able to mount a Mac format, but if it is ExFAT, it should be able to mount the file system if it is still working.

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Answer 4

cataclysmic Author

Level 1

5 points

May 29, 2022 9:08 PM in response to jeffreythefrog

Thanks. I'm *not* using any of SanDisk's preloaded software. I can't remember if I formatted it before using it---I probably didn't, in which case it's still in the factory exFat format.

Unfortunately, all of my backups of my mac have been regularly updated, so I don't have a bootable one with an older OS. This is a smart idea though---wish I hadn't done my last comprehensive backup drive updates last month...

**Two more clues**

I also tried the drive on a Windows PC. The PC recognized the drive and stated it was "working correctly" in the status bar, but again, it wouldn't mount and I was unable to access files....

One last oddity is that Activity Monitor shows that diskarbitrationd continuously runs and uses ~7% of my processor when the not-working-SSD is connected. This does not occur when I have other, working SSD's connected to my Mac.

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Answer 5

cataclysmic Author

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5 points

May 30, 2022 7:02 PM in response to Barney-15E

Thanks for the replies. I have tried numerous cables that have been tested/working with other drives (USB-C to USB-C, USB-C to USB 3, etc.) to no avail.

Here's all of the info I can get when it's plugged into a friend's Windows 10 machine (which recognizes the drive as a location but won't allow me to browse files). I don't see a format listed.

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Answer 6

Barney-15E

Level 10

122,186 points

May 30, 2022 7:13 PM in response to cataclysmic

It’s not possible to tell. Since it can’t recognize any Mac Formats, that doesn’t tell you much, except it is either not ExFAT as you thought, or it is damaged. NTFS is the standard format, but I have never used a Sandisk SSD.

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External SSD won't mount/missing in DiskUtility, but appears in SystemProfiler--help!

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