Formatting a usb drive

guldo · 10-08-2005, 09:28 AM

Hello.
I have a usb key I'd like to use.
So far it's been used on Windows (not by me), but it no longer works...
(don't know the details)

What I've tried is to erase all partitions and create a new one.
Unfortunately:
(parted) mkpartfs primary vfat 0% 100%
Error: Unable to open /dev/sda - unrecognised disk label.

What can I do to fix it?

Thanks

macemoneta · 10-08-2005, 01:14 PM

Many of these USB keys that I've seen aren't partitioned - they are like floppy disks. You can format the entire units as unpartitioned mountable space with:

mkdosfs -F 32 /dev/sda

If you want to partition the space, you can try wiping the device partition table with:

dd if=/dev/zero of=/dev/sda bs=512 count=10

You can also try another partitioning tool, like fdisk.

guldo · 10-08-2005, 01:23 PM

Thanks.
I've tried both, but each time:
# mount /mnt/usbkey/
mount: /dev/sda1 is not a valid block device

What should I check next?

macemoneta · 10-08-2005, 01:34 PM

If you format the entire drive unpartitioned, then you want to mount /dev/sda, not /dev/sda1 (there is no partition "1").

guldo · 10-08-2005, 02:36 PM

Thanks for the reply.

# mount -t vfat /dev/sda /mnt/usbkey/
mount: /dev/sda is not a block device (maybe try `-o loop'?)
# mount -t vfat -o loop /dev/sda /mnt/usbkey/
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
missing codepage or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

# dmesg
...
FAT: bogus number of reserved sectors
VFS: Can't find a valid FAT filesystem on dev loop0.

macemoneta · 10-08-2005, 03:00 PM

It's not a loopback device (a filesystem in a file), so you do not want to use the loop option.

What is the sequence of commands you issued to the device? If you wiped out the partition table with dd, then this is what I would expect.

Format, then mount:

mkdosfs -F 32 /dev/sda
mount -t vfat /dev/sda /mnt/usbkey/

guldo · 10-08-2005, 04:38 PM

(23:36:51)debian:~$ dd if=/dev/zero of=/dev/sda bs=512 count=10
10+0 records in
10+0 records out
5120 bytes transferred in 0.000736 seconds (6956872 bytes/sec)
(23:36:58)debian:~$ mkdosfs -F 32 /dev/sda
mkdosfs 2.11 (12 Mar 2005)
mkdosfs: Too few blocks for viable file system
(23:37:11)debian:~$ mount -t vfat /dev/sda /mnt/usbkey/
mount: /dev/sda is not a block device (maybe try `-o loop'?)

I'm puzzled...

macemoneta · 10-08-2005, 04:50 PM

Quote:

Originally posted by guldo

(23:36:58)debian:~$ mkdosfs -F 32 /dev/sda
mkdosfs 2.11 (12 Mar 2005)
mkdosfs: Too few blocks for viable file system
(23:37:11)debian:~$ mount -t vfat /dev/sda /mnt/usbkey/
mount: /dev/sda is not a block device (maybe try `-o loop'?)

I'm puzzled...

The format failed, so there is no use trying to mount. The device may be too small to support vfat, so you can try fat by just removing the "-F 32" option:

mkdosfs /dev/sda

guldo · 10-08-2005, 06:10 PM

Thanks for the hint

Unfortunately:
(01:08:29)debian:guldo# mkdosfs /dev/sda
mkdosfs 2.11 (12 Mar 2005)
mkdosfs: Attempting to create a too large file system
(01:08:35)debian:guldo# mkdosfs -F 12 /dev/sda
mkdosfs 2.11 (12 Mar 2005)
mkdosfs: Attempting to create a too large file system

macemoneta · 10-08-2005, 09:00 PM

Then your device is broken - it's not indicating a valid size. You can try overriding the default detection by specifying the block count:

mkdosfs -F 32 /dev/sda <count>

where count is:

MB * 2048

For example, a 256MB unit would have a block count of:

256 * 2048 = 524288

guldo · 10-09-2005, 05:32 AM

Thank you.
What does the following mean?
(12:30:47)debian:~# mkdosfs -F 32 /dev/sda 524288
mkdosfs 2.11 (12 Mar 2005)
Warning: block count mismatch: found 5 but assuming 524288.

macemoneta · 10-09-2005, 11:16 AM

It means that your device reported that it has a capacity of 5 blocks (which is 2.5K) while you specified that it actually contains 524288 blocks (256MB). The device was formatted as if it had the larger capacity.

Unless you are running a broken kernel, the device is reporting a bogus capacity.