Restore/Format USB Flash Drive

Posted: September 23, 2008 in LINUX, SYSTEM UTILITY
Tags: , ,

Who does not have a flash memory USB drive? (128Mb – 16Gb…) Everybody does, even my dog, if I had one, would have it. However, sometimes these little dongles can be tricky to use if they are not properly formatted. The usual format for the flash memory USB drive is FAT16, and it is understood by many operating systems with no problem. But in case the drive is not formatted properly/or you think it is not formatted properly, you can always reformat it, and here is how.

The whole process consists of 5 steps ans takes about 15 seconds um.. if do it slowly.. )

WARNING: All the data will be lost from the flash UBS drive since we are going to reformat it.

We are going to use fdisk utility, so “for starters” here are available commands that you can use with fdisk:

a – toggle a bootable flag
b – edit bsd disklabel
c – toggle the dos compatibility flag
d – delete a partition
l – list known partition types
m – print this menu
n – add a new partition
o – create a new empty DOS partition table
p – print the partition table
q – quit without saving changes
s – create a new empty Sun disklabel
t – change a partition’s system id
u – change display/entry units
v – verify the partition table
w – write table to disk and exit
x – extra functionality (experts only)

Now let’s get to cooking a new and fresh flash memory USB drive…

Step 1. Run fdisk via sudo on your USB flash drive device:

user@host:~$ sudo fdisk /dev/sdb

enter “p” command to list current partition table of the USB drive:

Command (m for help): p
Disk /dev/sdb: 1039 MB, 1039663104 bytes
32 heads, 62 sectors/track, 1023 cylinders
Units = cylinders of 1984 * 512 = 1015808 bytes
Disk identifier: 0xf1f494df
Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        1023     1014785   83  Linux

Here you will see whatever partition (if any) currently present. In my case (above) it is a “Linux” partition, in your case it may be something different. But it does not really matter, because we are going to delete it anyway:

Step 2. Enter “d” command to delete existing partition (if you have any). If you have several, delete several by using”d” command multiple times:

Command (m for help): d
Selected partition 1

Step 3. Now let’s get to business and enter “n” command to create a new partition:

Command (m for help): n
Command action
e   extended
p   primary partition (1-4)
Partition number (1-4): 1
First cylinder (1-1023, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-1023, default 1023):
Using default value 1023

As you can see from above, I entered “1” for “Partition number”, and hit enter key twice to leave everything by default.

Now let us list current partitions with “p” command again:

Command (m for help): p
Disk /dev/sdb: 1039 MB, 1039663104 bytes
32 heads, 62 sectors/track, 1023 cylinders
Units = cylinders of 1984 * 512 = 1015808 bytes
Disk identifier: 0xf1f494df
Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        1023     1014785   83  Linux

We have a single “Linux” partition which is fine (for now).

Step 4. Time to actually apply our changes, so enter a “w” command that will write out all the changes to the USB drive.

Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.

fdisk will write all the changes to the USB drive and exit. But we are not done yet. Our goal is to make a (in this case) FAT16 partition, so this USB drive can be read by most operating systems.

Step 5. For that we will use mkfs.vfat utility:

user@host:~$ sudo mkfs.vfat -F 16 /dev/sdb1
mkfs.vfat 2.11 (12 Mar 2005)

Now we are good to go! It was easy, as I promised )

Let’s look at the new USB drive now. Mounting it first:

user@host:~$ sudo mount /dev/sdb1 /mnt/flashka/
user@host:~$ cd /mnt/flashka/
user@host:/mnt/flashka$ ls -l
total 0

Checking what it has under the hood:

user@host:/mnt/flashka$ df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sdb1             991M     0  991M   0% /mnt/flashka

It has 991Mb which is what they call 1Gb flash memory USB drive! )

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  1. i want to format the pendrive but this drive is have the write protection disk

    so i try follow your instruction

    sudo fdisk /dev/sdb
    it said this: You will not be able to write the partition table.

    step 2 n 3 is ok

    step 4
    Command (m for help): w
    fdisk: unable to write /dev/sdb: Bad file descriptor

    then when i check the drive, it not formatted yet…

    so, how can i solve this problem…

  2. Rock Bhai says:

    after step 4 I am getting:
    WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
    The kernel still uses the old table. The new table will be used at
    the next reboot or after you run partprobe(8) or kpartx(8)

    Error closing file

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