> I have a SanDisk Ultra Flair USB 3.0 device that doesn't appear to be
> properly recognized. It doesn't appear in an "fdisk -l" output and not
> automatically mounted on the filesystem as other devices are. It does
> appear to be detected, however:
>
> [498296.376209] usb 2-3: USB disconnect, device number 7
> [498298.800214] usb 2-3: new SuperSpeed USB device number 8 using
> xhci_hcd [498298.812856] usb 2-3: New USB device found, idVendor=0781,
> idProduct=5591, bcdDevice= 1.00
> [498298.812867] usb 2-3: New USB device strings: Mfr=1, Product=2,
> SerialNumber=3
> [498298.812871] usb 2-3: Product: Ultra USB 3.0
> [498298.812874] usb 2-3: Manufacturer: SanDisk
> [498298.812877] usb 2-3: SerialNumber: 4C530001030516102474
> [498298.814899] usb-storage 2-3:1.0: USB Mass Storage device detected
> [498298.815110] scsi host11: usb-storage 2-3:1.0
> [498298.983388] usb 2-3: reset SuperSpeed USB device number 8 using
> xhci_hcd
>
> It's not that old, and certainly doesn't have many hours on it. Are
> there any other ways I can try to access it before determining it's
> defective?

Thank you all for your help. I didn't realize that my Win10 VM was automatically mounting it, making it unavailable to Linux.

I also had tried on my Win10 laptop, but because I had previously used it as a sysrescuecd, it was unable to recognize/mount it.

What does parted have to say? Ditto mount.

FWIW, I have a SanDisk 1TB Ultra microSDXC UHS-I, which came formatted
for extfat and would not mount until reformatted.