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slimjim 01-03-2007 11:20 AM

usb flash drive / ext2 oddness
 
Hiya,

I bought a 1GB USB flash stick the other week, and today I decided to put an ext2 filesystem on it, to make it a shade more Linux-friendly (and because I like to tinker).

So I did the necessary from fdisk, and ended up with this:


Code:

Disk /dev/sdf: 1030 MB, 1030225920 bytes
32 heads, 62 sectors/track, 1014 cylinders
Units = cylinders of 1984 * 512 = 1015808 bytes

  Device Boot      Start        End      Blocks  Id  System
/dev/sdf1              1        1014    1005857  83  Linux

All well and good. So I ran mke2fs:

Code:

sauce:/home/jg# mke2fs /dev/sdf1
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
125952 inodes, 251464 blocks
12573 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=260046848
8 block groups
32768 blocks per group, 32768 fragments per group
15744 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376

Writing inode tables: done                           
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 35 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
sauce:/home/jg#

Kushti! At this point, I can mount the usb stick with no problem:

Code:

sauce:/mnt/pinkstick# df -m .
Filesystem          1M-blocks      Used Available Use% Mounted on
/dev/sdf1                  967        2      917  1% /mnt/pinkstick

Yes, it's pink. Harder to misplace :D

The trouble is, if I then unmount and (sorry about this, I was brought up on Benny Hill and Carry On films) reinsert my pink stick ..

Code:

sauce:~# umount /mnt/pinkstick/
sauce:~# ls -l /dev/sdf1
brw-rw---- 1 root disk 8, 81 Jan  3 17:06 /dev/sdf1
sauce:~# # stick physically removed and reinserted at this point
sauce:~# ls -l /dev/sdf1
ls: /dev/sdf1: No such file or directory
sauce:~#

.. I appear to lose the partition. Interestingly, I can still see it from fdisk, but it's gone from the device tree, and obviously I can't mount it, read from it or write to it.

Code:

sauce:~# fdisk /dev/sdf

Command (m for help): p

Disk /dev/sdf: 1030 MB, 1030225920 bytes
32 heads, 62 sectors/track, 1014 cylinders
Units = cylinders of 1984 * 512 = 1015808 bytes

  Device Boot      Start        End      Blocks  Id  System
/dev/sdf1              1        1014    1005857  83  Linux

Command (m for help): q

sauce:~# ls -l /dev/sdf1
ls: /dev/sdf1: No such file or directory
sauce:~# ]

.. any thoughts?

Cheers
Slim

Lenard 01-03-2007 11:28 AM

And why do you think you can read a partition that is not mounted???

You have a mountpoint for the partition use it;

mount -t ext2 /dev/sdf1

ls -l /mnt/pinkstick

slimjim 01-03-2007 12:10 PM

I don't think that.

The problem, as I stated, is that it's not possible to mount it:

Code:

sauce:/home/jg#  mount /mnt/pinkstick/
mount: special device /dev/sdf1 does not exist
sauce:/home/jg# grep pink /etc/fstab
/dev/sdf1 /mnt/pinkstick ext2 user,noauto 0 0
sauce:/home/jg#


Lenard 01-03-2007 05:20 PM

OK, then as a suggestion remove the device wait a bit then insert the device and check the messages;

tail /var/log/messages or tail dmesg

Maybe the device is no longer known as /dev/sdf


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