I have attached a USB device which is an enclosure for an NVMe M.2 storage unit. Both devices, the enclosure and the media, had been known to be in working order during their last use.

When I connect the device, the following kernel log appears:

kernel: usb 1-1.1: new high-speed USB device number 10 using ehci-pci
kernel: usb 1-1.1: New USB device found, idVendor=152d, idProduct=0583, bcdDevice= 2.08
kernel: usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
kernel: usb 1-1.1: Product: USB to PCIE Bridge
kernel: usb 1-1.1: Manufacturer: JMicron
kernel: usb 1-1.1: SerialNumber: 0123456789ABCDEF
kernel: usb 1-1.1: UAS is ignored for this device, using usb-storage instead
kernel: usb-storage 1-1.1:1.0: USB Mass Storage device detected
kernel: usb-storage 1-1.1:1.0: Quirks match for vid 152d pid 0583: 800000
kernel: scsi host6: usb-storage 1-1.1:1.0
kernel: scsi 6:0:0:0: Direct-Access     JMicron  Generic          0208 PQ: 0 ANSI: 6
kernel: sd 6:0:0:0: Attached scsi generic sg2 type 0
kernel: sd 6:0:0:0: [sdb] Unit Not Ready
kernel: sd 6:0:0:0: [sdb] Sense Key : Hardware Error [current] 
kernel: sd 6:0:0:0: [sdb] ASC=0x44 <<vendor>>ASCQ=0x81 

The messages are not showing in a web search. What is their meaning? How may I attempt to resolve?

  • As it turns out, the storage device was simply completely dysfunctional. It was inoperative on any host. The error message was just an obtuse way of saying, Your card is fried, get a new one.
    – brainchild
    Oct 9, 2022 at 4:58

2 Answers 2


The messages are not showing in a web search.

You can easily find them in the SCSI spec. ASCQ >= 0x80 is a vendor-specific error.

What is their meaning?

When the USB device gets connected, it is identified as a block storage device. The command set for those devices is basically SCSI (transported over USB). So the kernel issues a few SCSI commands to that device, for example to find out the capacity. Your USB-to-NVM bridge chip answers with "unit not ready", for whatever reason (for example, because the firmware is still initializing itself).

How may I attempt to resolve?

That entirely depends on what happens next, which you didn't show.

The kernel will re-send those commands. If they succeed (no error messages, you see the capacity etc. in dmesg) you don't need to do anything.

If they persist, and you cannot access the storage, first I'd check if the NVM is seated properly.

If it is, my next guess would be "bridge chip broken" or "NVM storage not compatible with that particular bridge chip".

  • More messages do appear after time, of largely the same variety, running in a loop. The storage media is not found even after time. Physical inspections reveals no problems with the seating.
    – brainchild
    Mar 29, 2022 at 2:18
  • You only wrote "both components have been in working condition last time they got used", but did they ever work in that combination? And if you (or some friends) have another enclosure and/or media, you can swap components to determine if it's one or the other, or some particular combination.
    – dirkt
    Mar 29, 2022 at 5:30
  • The bridge has been used only with other storage cards. The card has been used only on a main board. The combination was never used, until now, as I need to use the card with a bridge to retrieve data on another host. I have access to no other bridge.
    – brainchild
    Mar 29, 2022 at 7:33
  • Then given those constraints, I have no more ideas.
    – dirkt
    Mar 29, 2022 at 9:27

I had almost the exact same error messages. In my case the drive was a standard external "off the shelf" Western Digital 6tb hard disk w/USB enclosure.

Issue occured after power failure to the property.

Multiple reboots, and unplugging/replugging/changing of USB cables would not fix it - dmesg -w showed the same errors happened every time the drive was plugged in.

The solution in my case was: boot up the system, have the drive attached via USB, and then manually pull and reconnect the power cable to the external drive enclosure itself.

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