Layout of a USB Key Created by mk-boot-usb

Note: This page applies to version 08h or later. For older versions, see this page.

layout example Suppose that mk-boot-usb reports your usb key to be 1976MB in size. Then you give the command mk-boot-usb -d /dev/sdx -z '476 300 400 700' -4 100. Note that the numbers, including the one after the -4 option, add up to 1976. This will create a disk layout like the one in the picture:

  1. (primary) partition 1 is formatted as a 476MB (roughly) vfat that MS Windows can see;
  2. (extended) partition 2 contains three ext2 partitions each of size 300MB, 400MB, and 700MB (roughly) for you to copy 3 live cd contents into;
  3. (primary) partition 4 is formatted as a 100MB (roughly) ext2 that holds the boot files, namely grub and ttylinux.

Version 08g and earlier used a simpler layout (without partition 4) and stored boot files in the vfat partition. Naive MS Windows users sometimes accidentally mess up with the most important boot files and make the key non-bootable. This new layout is used in version 08h and later to prevent that.

When you don't specify the -4 option, the default is -4 24, meaning only 24MB is used for grub and ttylinux.

When cloning one usb key to another, the exact layout is copied except that the size of partition 1 may change. That is, you cannot specify the layout of the destination usb key while cloning. Partition 1 will grow or shrink as necessary according to the difference between the sizes of the source and the destination usb key.