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I just installed Debian. Now when I try to boot Knoppix, it hangs on "Searching for Knoppix 7 in: /dev/sda6", which is the swap partition. Since Knoppix is choking on this, I'd like it to bypass searching the hard drive partitions for itself and instead boot from the USB directly.

I'm hoping I can get Knoppix to boot using the "knoppix fromhd=" or "knoppix bootfrom=" options to specify the USB drive so that Knoppix skips checking the hard drive. But how can I find out what Knoppix is calling my USB drive so I can specify it instead of the hard drive?

The reason I'm using Knoppix in the first place is that there's a problem with the GRUB installation with Debian, so I'm not able to boot from the hard drive to find out the name of the USB drive.

Update:

It turns out that for a live USB, you want knoppix fromhd=, not knoppix bootfrom, which is for when you want to point to an .iso. The USB drive was /dev/sdb, which I found out when Knoppix booted after about 20 minutes. The question still stands though: was there a way to find this out at boot?

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1 Answer 1

Linux hard drive enumeration simulation algorithm for humans

  1. Count the number of hard drives in your system
    • including external hard drives and USB memory peripheral devices
  2. Enumerate all characters in the English alphabet
    • starting with 1 = a, and ascending in natural order
  3. Correlate empirically found number of hard drives with an English letter (see notes)

Notes:

a. If the system has SATA hard drives and USB hard drives, the kernel will enumerate the former before the latter, such that any USB sticks or external drives will appear assigned to characters succeeding the characters assigned to non-USB drives.

b. USB drives are enumerated according their respective channels as outlines in the manual of your motherboard. On some motherboards, this information is visible on the printed circuit board. USB drive connected to the first USB channel will be enumerated immediately following the last enumerated SATA device (USB=SATA=SCSI when it comes to device files).

c. On systems with no SATA devices, the USB drives will begin enumeration from the letter a.

d. For systems with more 26 hard drives, invest in more capacious drives.

Example

  1. There are two hard drives and three USB drives in my system. One of the hard drives is connected on an old IDE channel.

  2. 1=a, 2=b, 3=c, 4=d, 5=e, 6=f, 7=g, 8=h, 9=i, 10=j, 11=k, 12=l, 13=m, 14=n, 15=o, 16=p, 17=q, 18=r, 19=s, 20=t, 21=u, 22=v, 23=w, 24=x, 25=y, 26=z

  3. 5=e. According to note b and a the first USB drive will be "b" while the last one will be "d". Hence my root device is assigned to one of those letters, I shall trial and err until I find the correct one*

* The human mind displays an astonishing capacity for improvisation and problem solving

Glossary

  • hard drive: Block device capable of holding a filesystem
  • SATA: Serial ATA
  • PATA: IDE
  • IDE: Integrated Device Electronics
  • ATA: American Trucking Associations

References

Multi Disk HOWTO: 12.2. Drives and Partitions
Installation HOWTO: 6.5.2. Using fdisk and cfdisk

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