This is a very weird scenario. I am trying to mount a USB 3.0 (using Debian 9). The USB drive gets auto-mounted on two of the three USB ports on my laptop. Until last night, it was auto-mounting on all three ports.

The port in question is working with other USB drives so the port hardware is working. lsusb does seem to show the device but it is recognized differently on ports that work and the one where it doesn't.

I read somewhere that perhaps auto-suspend was to blame. I disabled that but to no avail.

lsblk does not show the device. Also, whereas dmesg (output below) shows activity at sdb, /dev/sdb does not exist. I am going crazy trying to figure this one out and extensive googling hasn't help.

dmesg | grep SCSI output is shown:

[ 0.000000] ACPI: SSDT 0x00000000DCFDC000 0011FA (v01 LENOVO SaSsdt 00003000 INTL 20120711)
[ 2.447802] sd 0:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/466 GiB)
[ 2.447805] sd 0:0:0:0: [sda] 4096-byte physical blocks
[ 2.447837] sd 0:0:0:0: [sda] Write Protect is off
[ 2.447840] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
[ 2.447852] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 2.503160] sda: sda1 sda2 sda3
[ 2.503598] sd 0:0:0:0: [sda] Attached SCSI disk
[ 3.300233] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[ 6.596745] EXT4-fs (sda1): re-mounted. Opts: errors=remount-ro
[ 8.872000] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 11.947744] Adding 8788988k swap on /dev/sda2. Priority:-1 extents:1 across:8788988k FS
[ 13.131680] EXT4-fs (sda3): mounted filesystem with ordered data mode. Opts: (null)
[ 235.446439] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 235.447222] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 316.185282] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 316.186126] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 333.899546] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 333.900334] sd 6:0:0:0: [sdb] 125829120 512-byte logical blocks: (64.4 GB/60.0 GiB)
[ 333.900977] sd 6:0:0:0: [sdb] Write Protect is off
[ 333.900983] sd 6:0:0:0: [sdb] Mode Sense: 43 00 00 00
[ 333.901626] sd 6:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 333.907446] sdb: sdb1
[ 333.910313] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 446.792222] sd 6:0:0:0: [sdb] Synchronizing SCSI cache
[ 446.792266] sd 6:0:0:0: [sdb] Synchronize Cache(10) failed: Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
[ 453.448378] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 453.449203] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 663.997101] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 663.997740] sd 6:0:0:0: [sdb] 125829120 512-byte logical blocks: (64.4 GB/60.0 GiB)
[ 663.998368] sd 6:0:0:0: [sdb] Write Protect is off
[ 663.998372] sd 6:0:0:0: [sdb] Mode Sense: 43 00 00 00
[ 663.998997] sd 6:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 664.003528] sdb: sdb1
[ 664.005774] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 981.680985] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 981.681865] sd 6:0:0:0: [sdb] Attached SCSI removable disk
[ 2207.496978] sd 6:0:0:0: Attached scsi generic sg2 type 0
[ 2207.497704] sd 6:0:0:0: [sdb] Attached SCSI removable disk

That, as you correctly noticed, doesn't make much sense. Don't sweat. Look for answers that don't make much sense.

I got a boatload of that sort of issue which was solved by installing on a clean partition and not upgrading. Sometimes it's a power off that's required. Nothing drastic may be wrong, you're not cracking up, just your box apparently is :-P.

Putting USB devices on a powered hub seems to help with quirks like this. Voltage is lost over distance, so try shorter cables if that's not an option. Sometimes just putting a hub, even a passive one between helps. Although it might just be unplugging and re-plugging a few times to remove the oxidation from the parts that touch helps.

Shadow_7 it can't be voltage loss. I am connecting the USB directly into the port of the laptop. But thanks for reply.

A lot of laptops are under-spec'd when it comes to USB voltage. Every little bit to have "better" battery life than the competition. Plus those specs get worse with age. A powered usb HUB will supply an appropriate voltage for hungry devices.

Oh this sounds like an issue I have. I got four (4) 3.0 USB ports on my laptop. It still does this from time to time, and it turns out for me, to be finicky about the cable I use with the device to attach the hdd to the usb port. Using this https://www.ebay.com/itm/USB-3-0-To-...r=571565488304
and a compatible cable.

At times I still end up fiddling with the cables, switching them until I get one to work with the device I use to connect it.

As I use both the external HDDs (WD for me) and internal laptop 2.5" hdds as external HDD's, the power is not the issue, but the cables.

sometimes, I'll plug them in and reboot. Then they get picked up by the kernel at this time.

Which actually just happened to me, just moments ago before I seen this post, I had to fiddle with the cables. Switching them cables around until I got all three HDDs to 'hook up' via auto mount. So yes this is an on going quirk I have to deal with. Because the cables are good and work. It is just a question of when and for which one and such. It is one of them situations whare ya got a work with it until it works. For me anyways.

IIRC, there's some power surge wi9th solid state drives that not all ports supply. The fact is, the port should be good for half an amp. The practice is, they handle that power surge poorly.

Insert the stick and run in a terminal. That should catch most initial errors. If something goes on complaining longer than that, you'll have isolated your fault. My perfectly functional powered usb drive throws up a It all sounds a bit hysterical, but it works every time. The drive is waking up too, which doesn't help.