USB pen -- strange error

From: Daniel Arteaga (darteaga_at_REMOVEALLUPPERCASEya.com.INVALID)
Date: 11/27/04 

Date: Sat, 27 Nov 2004 13:45:16 +0100

Hi all,

I have a 256 MB USB pen, and I have formatted it with a single fat32
partition. When I insert the pen in the usb port, and I try

mount -t vfat /dev/sdb1 /mnt/usb

I get

mount: the special device /dev/sdb1 does not exist.

At the moment of inserting the USB pen, I get the following dmesg:

usb 5-7: new high speed USB device using address 4
scsi5 : SCSI emulation for USB Mass Storage devices
   Vendor: Generic Model: USB Flash Disk Rev: 2.00
   Type: Direct-Access ANSI SCSI revision: 02
sdf: Unit Not Ready, sense:
Current : sense key Unit Attention
Additional sense: Not ready to ready change, medium may have changed
sdf : READ CAPACITY failed.
sdf : status=1, message=00, host=0, driver=08
Current sd: sense key Unit Attention
Additional sense: Not ready to ready change, medium may have changed
sdf: test WP failed, assume Write Enabled
sdf: assuming drive cache: write through
sdf: Unit Not Ready, sense:
Current : sense key Unit Attention
Additional sense: Not ready to ready change, medium may have changed
sdf : READ CAPACITY failed.
sdf : status=1, message=00, host=0, driver=08
Current sd: sense key Unit Attention
Additional sense: Not ready to ready change, medium may have changed
sdf: test WP failed, assume Write Enabled
sdf: assuming drive cache: write through
sdf: Unit Not Ready, sense:
Current : sense key Unit Attention
Additional sense: Not ready to ready change, medium may have changed
sdf : READ CAPACITY failed.
sdf : status=1, message=00, host=0, driver=08
Current sd: sense key Unit Attention
Additional sense: Not ready to ready change, medium may have changed
sdf: test WP failed, assume Write Enabled
sdf: assuming drive cache: write through
  /dev/scsi/host5/bus0/target0/lun0:end_request: I/O error, dev sdf,
sector 0
Buffer I/O error on device sdf, logical block 0
Buffer I/O error on device sdf, logical block 0
Buffer I/O error on device sdf, logical block 262143
Buffer I/O error on device sdf, logical block 262143
Buffer I/O error on device sdf, logical block 0
ldm_validate_partition_table(): Disk read failed.
Buffer I/O error on device sdf, logical block 0
  unable to read partition table
  /dev/scsi/host5/bus0/target0/lun0:<3>Buffer I/O error on device sdf,
logical block 0
Buffer I/O error on device sdf, logical block 262143
Buffer I/O error on device sdf, logical block 0
ldm_validate_partition_table(): Disk read failed.
Buffer I/O error on device sdf, logical block 0
  unable to read partition table
Attached scsi removable disk sdf at scsi5, channel 0, id 0, lun 0
Attached scsi generic sg5 at scsi5, channel 0, id 0, lun 0, type 0
USB Mass Storage device found at 4

Now here comes the strange part. If now I write as root:

fdisk -l /dev/sdf

Device Boot Start End Blocks Id System
/dev/sdf1 * 1 1599 255716 b W95 FAT32

in dmesg appears:

USB Mass Storage device found at 4
SCSI device sdf: 511488 512-byte hdwr sectors (262 MB)
sdf: Write Protect is off
sdf: Mode Sense: 03 00 00 00
sdf: assuming drive cache: write through
SCSI device sdf: 511488 512-byte hdwr sectors (262 MB)
sdf: Write Protect is off
sdf: Mode Sense: 03 00 00 00
sdf: assuming drive cache: write through
  /dev/scsi/host5/bus0/target0/lun0: p1

and then I can correctly mount the USB pen without any further problem.

I'm working with Mandrake 10.1 and kernel 2.6.8.1.

I am really puzzled. I searched on the net without any results. It seems
that the pen it is not correctly recognized when it is inserted, but it
is recognized later on when the disk is read again.

Thank you for your help,

Dani