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