I tried to partition my microSD card and it was unable to work.  I follwed the instructions given by

http://www.gumstix.net/Setup-and-Programming/view/Overo-Setup-and-Programming/Creating-a-bootable-microSD-card/111.html

and it is unable to do the task.

td@TDlaptop:~$ sudo fdisk /dev/sdb
You will not be able to write the partition table.

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): c
DOS Compatibility flag is not set

Command (m for help): m
Command action
   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)

Command (m for help): c
DOS Compatibility flag is set

Command (m for help): o
Building a new DOS disklabel with disk identifier 0x20b56785.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): c
DOS Compatibility flag is not set

Command (m for help): o
Building a new DOS disklabel with disk identifier 0xf5489884.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: cylinders as display units are deprecated. Use command 'u' to
         change units to sectors.

Command (m for help): p

Disk /dev/sdb: 1977 MB, 1977614336 bytes
255 heads, 63 sectors/track, 240 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xf5489884

   Device Boot      Start         End      Blocks   Id  System

Command (m for help): x

Expert command (m for help): h
Number of heads (1-256, default 255): 255

Expert command (m for help): s
Number of sectors (1-63, default 63): 63

Expert command (m for help): c
Number of cylinders (1-1048576, default 240): 247

Expert command (m for help): r

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-247, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-247, default 247): +32M

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): c
Changed system type of partition 1 to c (W95 FAT32 (LBA))

Command (m for help): a
Partition number (1-4): 1

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (5-247, default 5): 6
Last cylinder, +cylinders or +size{K,M,G} (6-247, default 247): 247

Command (m for help): p

Disk /dev/sdb: 1977 MB, 1977614336 bytes
255 heads, 63 sectors/track, 247 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xf5489884

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1           5       39138    c  W95 FAT32 (LBA)
/dev/sdb2               6         247     1943865   83  Linux

Command (m for help): w

Unable to write /dev/sdb


--
Thomas Davis
Jackson State University
Computer Engineering Major