After a bit of a struggle yesterday to get ALSA working (it is
now working without anything in /etc/modprobe.d/alsa-base.conf),
my machine (Devuan jessie) did an automatic backup last night to
a WD Passport.

Although I can mount it and access its contents, when I plug it
in, dmesg says:

usb 3-12: new full-speed USB device number 49 using xhci_hcd
usb 3-12: New USB device found, idVendor=08bb, idProduct=2904
usb 3-12: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 3-12: Product: USB Audio CODEC
usb 3-12: Manufacturer: Burr-Brown from TI
usb 3-12: ep 0x85 - rounding interval to 64 microframes, ep desc
says 80 microframes
input: Burr-Brown from TI USB Audio CODEC as /devices/pci0000:
00/0000:00:14.0/usb3/3-12/3-12:1.3/0003:08BB:2904.0009/input/input22
hid-generic 0003:08BB:2904.0009: input,hidraw2: USB HID v1.00 Device
[Burr-Brown from TI USB Audio CODEC ] on usb-0000:00:14.0-12/input3

When I plug in a USB key, it automounts and dmesg reports that the
partition can be seen:

...
sd 38:0:0:0: [sdh] Mode Sense: 4f 00 00 00
sd 38:0:0:0: [sdh] Write cache: disabled, read cache: enabled, doesn't
support DPO or FUA
sdh: sdh1
sd 38:0:0:0: [sdh] Attached SCSI removable disk
EXT4-fs (sdh1): recovery complete
EXT4-fs (sdh1): mounted filesystem with ordered data mode. Opts: (null)

I have three WD Passport drives with micro-USB OTG connectors. They are
seen and can be mounted. Dmesg says for example:

...
ses 41:0:0:1: Attached Enclosure device
ses 41:0:0:1: Attached scsi generic sg10 type 13
sd 41:0:0:0: [sdh] 1953458176 512-byte logical blocks: (1.00 TB/931 GiB)
sd 41:0:0:0: [sdh] Write Protect is off
sd 41:0:0:0: [sdh] Mode Sense: 47 00 10 08
sd 41:0:0:0: [sdh] No Caching mode page found
sd 41:0:0:0: [sdh] Assuming drive cache: write through
sdh: sdh1
sd 41:0:0:0: [sdh] Attached SCSI disk

But I have three older Passports with mini-A connectors. When
I plug them in, dmesg does not respond at all. No device interface
is constructed (no /dev/sd*1 except for the plugged in backup drive).

In short, USB keys with type A connectors automount as expected.
WD Passports with micro-USB OTB connectors can be mounted
and accessed. WD Passports with Mini-A connectors are not
seen.

Hald is running. The modules usb-core, usb-common, hid and usbhid
are loaded.

Haines Brown

I'd double check the hardware. Are the usb sockets worn? Are they compatible, or do you presume they're compatible because they fit. Many usb types have gone forth into the world, and not every plug fits every socket.

Usb power not enough to spin it up???