USB, format and then...

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USB, format and then...

#1 Post by huberte » Sat Aug 16, 2008 3:08 pm


firstable thanks for the beta. I'm a big noob but I did succeed to make my usb stick bootable (youhou !!!)

And then... Can I use it as a normal USB stick ?

Why the format by the way (partition table ?) ?


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Joined: Fri Jan 11, 2008 2:52 pm

Re: USB, format and then...

#2 Post by Icecube » Sun Aug 17, 2008 12:51 am

huberte wrote:And then... Can I use it as a normal USB stick ?
Yes, you can. But sometimes it can be that you USB stick becomes unbootable after you have copied and deleted a lot of files (I have this sometimes). You can make it bootable again by running syslnux -ma -d syslinux x: (change x: to the appropriate drive letter).
Search the forum for a longer explanation.
huberte wrote:Why the format by the way (partition table ?) ?
Some bioses are very picky about the way a USB thumb drive is formatted.
Syslinux documentation (usbkey.txt) wrote:The proper mode to boot a USB key drive in is "USB-HDD". That is the ONLY mode in which the C/H/S geometry encoded on the disk itself doesn't have to match what the BIOS thinks it is. Since geometry on USB drives is completely arbitrary, and can vary from BIOS to BIOS, this is the only mode which will work in general.

Some BIOSes have been reported (in particular, certain versions of the Award BIOS) that cannot boot USB keys in "USB-HDD" mode. This is a very serious BIOS bug, but it is unfortunately rather typical of the kind of quality we're seeing out of major BIOS vendors these days. On these BIOSes, you're generally stuck booting them in USB-ZIP mode.


A standard zipdrive (both the 100 MB and the 250 MB varieties) have a "geometry" of 64 heads, 32 sectors, and are partitioned devices with a single partition 4 (unlike most other media of this type which uses partition 1.) The 100 MB variety has 96 cylinders, and the 250 MB variety has 239 cylinders; but any number of cylinders will do as appropriate for the size device you have. For example, if your device reports when inserted into a Linux system:

usb-storage: device found at 4
Vendor: 32MB Model: HardDrive Rev: 1.88
Type: Direct-Access ANSI SCSI revision: 02
SCSI device sda: 64000 512-byte hdwr sectors (33 MB)

... you would have 64000/(64*32) = 31.25 cylinders; round down to 31.

The script "mkdiskimage" which is supplied with the syslinux distribution can be used to initialize USB keys in a Zip-like fashion. To do that, calculate the correct number of cylinders (31 in the example above), and, if your USB key is /dev/sda (CHECK THE KERNEL MESSAGES CAREFULLY - IF YOU ENTER THE WRONG DISK DRIVE IT CANNOT BE RECOVERED), run:
mkdiskimage -4 /dev/sda 0 64 32

(The 0 means automatically determine the size of the device, and -4 means mimic a zipdisk by using partition 4.)
Then you should be able to run
syslinux /dev/sda4

... and mount /dev/sda4 and put your files on it as needed.
If you are lucky, you can use the USB-HDD method.

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