Hey All

Hope someone can help out here cause I'm pretty confused. I'm running Debian Testing on a Pogoplug. I have a 4 port unpowered USB hub hooked up to the single USB port on the pogoplug. Plugged into the usb hub, I have one UPS power supply data cable, and two 1TB hard drives.

I used udev rules to make sure my usb hard drives always get mapped to /dev/usbdrive1 and /dev/usbdrive2. I then used LVM to merge the two to get a 2TB volume with an ext4 fs. Then I set it up to become active at boot and mount itself. Awesome. So far so good. I try a few reboots, everything is great.

Now comes the problem. I have a 500G USB hard drive that I also want to connect to act as a backup for important things. When I plug it in, it detects as /dev/sdc. And everything seems to work fine. I can still use the LVM, everything looks good. However, when I reboot, after the system comes up all I see is /dev/sda. No sign of /dev/sdb or sdc, and /dev/usbdrive1 and /dev/usbdrive2 are nowhere to be found. Looking at the output of usb-devices, I can definitely see the hard drives are being detected. They're just not showing up in /dev. This happened before I had the udev rules as well.

Any idea what might be going on?

EDIT: Here's something interesting from dmesg | more:

sd 2:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB)
sd 2:0:0:0: Attached scsi generic sg0 type 0
sd 2:0:0:0: [sda] Write Protect is off
sd 2:0:0:0: [sda] Mode Sense: 27 00 00 00
sd 2:0:0:0: [sda] Assuming drive cache: write through
usb-storage: device scan complete
sd 2:0:0:0: [sda] Assuming drive cache: write through
sda: sda1
sd 2:0:0:0: [sda] Assuming drive cache: write through
sd 2:0:0:0: [sda] Attached SCSI disk
usb 1-1.2: reset high speed USB device using orion-ehci and address 4
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
scsi 1:0:0:0: Direct-Access SAMSUNG HD103SI PQ: 0 ANSI: 2 CCS
sd 1:0:0:0: Attached scsi generic sg1 type 0
usb 1-1.2: reset high speed USB device using orion-ehci and address 4
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
usb-storage: device scan complete
sd 1:0:0:0: [sdb] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB)
sd 1:0:0:0: [sdb] Write Protect is off
sd 1:0:0:0: [sdb] Mode Sense: 28 00 00 00
sd 1:0:0:0: [sdb] Assuming drive cache: write through
sd 1:0:0:0: [sdb] Assuming drive cache: write through
sdb: sdb1
sd 1:0:0:0: [sdb] Assuming drive cache: write through
sd 1:0:0:0: [sdb] Attached SCSI disk
usb 1-1.2: reset high speed USB device using orion-ehci and address 4
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
usb-storage: device scan complete
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
usb 1-1.3: reset high speed USB device using orion-ehci and address 5
usb 1-1.3: can't restore configuration #1 (error=-71)
sd 1:0:0:0: [sdb] Unhandled error code
sd 1:0:0:0: [sdb] Result: hostbyte=0x07 driverbyte=0x00
end_request: I/O error, dev sdb, sector 0
Buffer I/O error on device sdb, logical block 0
usb 1-1.3: USB disconnect, address 5
scsi 1:0:0:0: [sdb] Unhandled error code
scsi 1:0:0:0: [sdb] Result: hostbyte=0x07 driverbyte=0x00
end_request: I/O error, dev sdb, sector 0
Buffer I/O error on device sdb, logical block 0
usb 1-1.3: new high speed USB device using orion-ehci and address 7
usb 1-1.3: configuration #1 chosen from 1 choice
scsi3 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 7
usb-storage: waiting for device to settle before scanning
usb 1-1.3: reset high speed USB device using orion-ehci and address 7
eth0: no IPv6 routers present
usb 1-1.3: reset high speed USB device using orion-ehci and address 7
usb 1-1.3: reset high speed USB device using orion-ehci and address 7
usb 1-1.3: reset high speed USB device using orion-ehci and address 7
usb-storage: device scan complete

I/O error. Only happens when the third drive is plugged in. Any ideas on how to resolve? Might it be the USB hub? The drive itself?

No idea what's going on but I've got a similar scenario. Backup drive is mapped to /dev/backup and it gets mounted but never shows up with 'fdisk -l'.

Figured it out. The fact it was an unpowered hub was the issue. I switch over to a powered hub and everything is awesome now.