I have read many entries on this same subject but can not find one to resolve my issue.

Problem: Mount a usb external drive using mount /dev/sdb1 /backup. Copy file to /backup and umount /dev/sdb1. Works fine. Then I mount again and list contents and it works fine. Unplug the drive and plug it back in try to mount and get the error that I must specify the filesystem.

I cat the /proc/partitions and it lists sdb1. If I search logs the last line says that it can't mount FAT system. I have tried to mount with many different fstypes but no luck. I believe re-booting the system will allow me to re-mount but I would like to avoid this.

I am using RedHat Ent. 3

Any suggestions on how to resolve this

Note: mount -t usbdevfs /dev/sdb1 /backup works but the contents are
001 002 003 devices drivers
None of this resembles what I actually backed up

'usbdevfs' is a special type, not meant to be used. When it is specified, it does not actually mount the device you told it, but a special device, which shows some of the internal info about usb. So that's not what you want to use.

You should paste in the output of your /var/log/syslog /var/log/messages, including the parts related to USB, when you unplug and replug the device.

Random guess, probably wrong, but maybe it's getting detected as another device name? So try mounting /dev/sdc1 or /dev/sdd1, etc

This is the tail of my messages file.
I tried /dev/sdc1 and /dev/sdd1. Did not work

Dec 5 12:36:56 jansrv kernel: I/O error: dev 08:11, sector 2
Dec 5 12:36:56 jansrv kernel: Device 08:11 not ready.
Dec 5 12:36:56 jansrv kernel: I/O error: dev 08:11, sector 64
Dec 5 12:36:56 jansrv kernel: Device 08:11 not ready.
Dec 5 12:36:56 jansrv kernel: I/O error: dev 08:11, sector 66
Dec 5 12:36:56 jansrv kernel: Device 08:11 not ready.
Dec 5 12:36:56 jansrv kernel: I/O error: dev 08:11, sector 0
Dec 5 12:36:56 jansrv kernel: FAT: unable to read boot sector