I am able to mount my USB FDD using /dev/sda, but that was just by luck. Based on the articles I found, I thought that would mount the Zip instead. Mount also failed for /dev/sd[b-f] saying each was not a valid block device, just like /dev/sda does when the FDD isn't plugged in.

As shown in the extract below, both devices (MITSUMI USB FDD 061M and USB Zip 250) are being recognized by the USB controllers, but I have not been able to figure out the /dev/ node is associated with the Zip drive.

Where can I look to see what /dev/ node I should use for plugged-in USB storage devices?

==== System information:
Distribution: Knoppix (Debian testing/sarge)
Kernel: 2.6.9
Computer: Dell Inspiron 1150 laptop

Extract from /proc/bus/usb/devices:

T: Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
B: Alloc= 0/900 us ( 0%), #Int= 0, #Iso= 0
D: Ver= 1.10 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0000 ProdID=0000 Rev= 2.06
S: Manufacturer=Linux 2.6.9 uhci_hcd
S: Product=Intel Corp. 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2
S: SerialNumber=0000:00:1d.1
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr= 0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 2 Ivl=255ms

T: Bus=02 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 MxCh= 0
D: Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=03ee ProdID=6901 Rev= 2.00
S: Manufacturer=MITSUMI
S: Product=MITSUMI USB FDD 061M
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA
I: If#= 0 Alt= 0 #EPs= 3 Cls=08(stor.) Sub=04 Prot=00 Driver=usb-storage
E: Ad=82(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=01(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=83(I) Atr=03(Int.) MxPS= 2 Ivl=127ms

T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh= 2
B: Alloc= 0/900 us ( 0%), #Int= 0, #Iso= 0
D: Ver= 1.10 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0000 ProdID=0000 Rev= 2.06
S: Manufacturer=Linux 2.6.9 uhci_hcd
S: Product=Intel Corp. 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1
S: SerialNumber=0000:00:1d.0
C:* #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr= 0mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub
E: Ad=81(I) Atr=03(Int.) MxPS= 2 Ivl=255ms

T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 3 Spd=12 MxCh= 0
D: Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1
P: Vendor=059b ProdID=0032 Rev= 3.00
S: Manufacturer=Iomega
S: Product=USB Zip 250
S: SerialNumber=803244684E853327
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=498mA
I: If#= 0 Alt= 0 #EPs= 3 Cls=08(stor.) Sub=06 Prot=50 Driver=ub
E: Ad=01(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=82(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=83(I) Atr=03(Int.) MxPS= 2 Ivl=32ms

assuming you're running hotplug, the easiest way is to just run "dmesg" after connecting a device, and it will normally tell you where it put it.

also if you're using udev as well, you might want to look into writing a few custom rules, which could make your usb floppy always go to /dev/usbfloppy etc...

Thank you for the quick reply. That worked great for the FDD. I edited /etc/fstab to define the floppy as /dev/sda. That lets me mount and umount it which is all I need.

I'm getting a bunch of "Buffer I/O error on device uba" messages for the Zip Drive though. I'll get back to the forum after I confirm that the disk really is readable using MSWin. I'm dual boot, so it will take a few minutes.

So much for the easy answer. The drive and disk work fine in WinXP. When I plug in the same drive with the same disk under Linux, I get the errors I mentioned before. The disk is a Iomega zip100 with the factory formatting in an Iomega USB Zip 250 drive. As before, /proc/bus/usb/devices confirms the drive type.

==== dmesg extract:
usb 1-1: new full speed USB device using address 3
uba: resid 18 len 0 act 0
uba: device 3 capacity nsec 50 bsize 512
uba: tag orig 0x3 reply 0x2
uba: made changed
uba: tag orig 0x4 reply 0x3
uba: device 3 capacity nsec 50 bsize 512
uba: tag orig 0x5 reply 0x4
uba: device 3 capacity nsec 50 bsize 512
uba:end_request: I/O error, dev uba, sector 0
Buffer I/O error on device uba, logical block 0
end_request: I/O error, dev uba, sector 2
Buffer I/O error on device uba, logical block 1
end_request: I/O error, dev uba, sector 4
Buffer I/O error on device uba, logical block 2
end_request: I/O error, dev uba, sector 6
Buffer I/O error on device uba, logical block 3
end_request: I/O error, dev uba, sector 6
Buffer I/O error on device uba, logical block 3
end_request: I/O error, dev uba, sector 4
Buffer I/O error on device uba, logical block 2
end_request: I/O error, dev uba, sector 2
Buffer I/O error on device uba, logical block 1
end_request: I/O error, dev uba, sector 0
Buffer I/O error on device uba, logical block 0
ldm_validate_partition_table(): Disk read failed.
end_request: I/O error, dev uba, sector 2
Buffer I/O error on device uba, logical block 1
end_request: I/O error, dev uba, sector 4
Buffer I/O error on device uba, logical block 2
end_request: I/O error, dev uba, sector 6
Buffer I/O error on device uba, logical block 3
end_request: I/O error, dev uba, sector 0
Buffer I/O error on device uba, logical block 0
unable to read partition table
uba:end_request: I/O error, dev uba, sector 2
Buffer I/O error on device uba, logical block 1
end_request: I/O error, dev uba, sector 4
Buffer I/O error on device uba, logical block 2
end_request: I/O error, dev uba, sector 6
Buffer I/O error on device uba, logical block 3
end_request: I/O error, dev uba, sector 0
Buffer I/O error on device uba, logical block 0
ldm_validate_partition_table(): Disk read failed.
end_request: I/O error, dev uba, sector 2
Buffer I/O error on device uba, logical block 1
end_request: I/O error, dev uba, sector 4
Buffer I/O error on device uba, logical block 2
end_request: I/O error, dev uba, sector 6
Buffer I/O error on device uba, logical block 3
end_request: I/O error, dev uba, sector 0
Buffer I/O error on device uba, logical block 0
unable to read partition table
====