| [e16e8f2] | 1 | The proper mode to boot a USB key drive in is "USB-HDD". That is the |
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| 2 | ONLY mode in which the C/H/S geometry encoded on the disk itself |
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| 3 | doesn't have to match what the BIOS thinks it is. Since geometry on |
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| 4 | USB drives is completely arbitrary, and can vary from BIOS to BIOS, |
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| 5 | this is the only mode which will work in general. |
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| 6 | |
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| 7 | Some BIOSes have been reported (in particular, certain versions of the |
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| 8 | Award BIOS) that cannot boot USB keys in "USB-HDD" mode. This is a |
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| 9 | very serious BIOS bug, but it is unfortunately rather typical of the |
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| 10 | kind of quality we're seeing out of major BIOS vendors these days. On |
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| 11 | these BIOSes, you're generally stuck booting them in USB-ZIP mode. |
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| 12 | |
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| 13 | THIS MEANS THE FILESYSTEM IMAGE ON THE DISK HAS TO HAVE A CORRECT |
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| 14 | ZIPDRIVE-COMPATIBLE GEOMETRY. |
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| 15 | |
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| 16 | A standard zipdrive (both the 100 MB and the 250 MB varieties) have a |
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| 17 | "geometry" of 64 heads, 32 sectors, and are partitioned devices with a |
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| 18 | single partition 4 (unlike most other media of this type which uses |
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| 19 | partition 1.) The 100 MB variety has 96 cylinders, and the 250 MB |
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| 20 | variety has 239 cylinders; but any number of cylinders will do as |
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| 21 | appropriate for the size device you have. For example, if your device |
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| 22 | reports when inserted into a Linux system: |
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| 23 | |
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| 24 | usb-storage: device found at 4 |
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| 25 | Vendor: 32MB Model: HardDrive Rev: 1.88 |
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| 26 | Type: Direct-Access ANSI SCSI revision: 02 |
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| 27 | SCSI device sda: 64000 512-byte hdwr sectors (33 MB) |
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| 28 | |
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| 29 | ... you would have 64000/(64*32) = 31.25 cylinders; round down to 31. |
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| 30 | |
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| 31 | The script "mkdiskimage" which is supplied with the syslinux |
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| 32 | distribution can be used to initialize USB keys in a Zip-like fashion. |
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| 33 | To do that, calculate the correct number of cylinders (31 in the |
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| 34 | example above), and, if your USB key is /dev/sda (CHECK THE KERNEL |
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| 35 | MESSAGES CAREFULLY - IF YOU ENTER THE WRONG DISK DRIVE IT CANNOT BE |
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| 36 | RECOVERED), run: |
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| 37 | |
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| 38 | mkdiskimage -4 /dev/sda 0 64 32 |
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| 39 | |
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| 40 | (The 0 means automatically determine the size of the device, and -4 |
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| 41 | means mimic a zipdisk by using partition 4.) |
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| 42 | |
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| 43 | Then you should be able to run |
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| 44 | |
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| 45 | syslinux /dev/sda4 |
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| 46 | |
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| 47 | ... and mount /dev/sda4 and put your files on it as needed. |
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