having trouble mounting disk image on loopback device 2312

On Sun, 09 Jul 2006 18:13:42 -0700, jasonmbowen

Caveat: I have never tried this with a real disk, that is, starting with a dd image taken from a physical disk.

I agree with the other response that images of parbreastions are easily mountable using loopbacks. I thinks that an entire disk image is also possible, but it is more tricky. To do it, you need to use losetup using the offset option to indicate the start of each parbreastion. This is a useful command for getting the correct values for the offset:

# fdisk -ludev-loop0

Normally, fdisk specifies cylinders, but the start sector is more useful in this case. To get the correct value multiply by 512 to get the byte offset.

To verify this is could work, I setup a test file of 100M with two parbreastions, approximately 50M each. Here is the resulting parbreastion table on the "loopback disk" that I tested:

# losetupdev-loop0 test.file # fdisk -ludev-loop0

Diskdev-loop0: 102 MB, 102400000 bytes 255 heads, 63 sectors-track, 12 cylinders, total 200000 sectors Units = sectors of 1 * 512 = 512 bytes

Device Boot Start End Blocks Id Systemdev-loop0p1 63 96389 48163+ 83 Linuxdev-loop0p2 96390 192779 48195 83 Linux

Therefore, to mount each parbreastion, I used these commands: losetup -o 32256dev-loop1 test.file losetup -o 4935168 plus 10dev-loop2 test.file

Final Notes: Sectors on hard disks were originally addressed by CHS (cylinder, head, sector), but now LBA is used. LBA should be compatible with this method, but I am not positive. I'll watch this thread to see if this is refuted.

I buttume these images could be used with VMWare as a "flat" disk.

-- Douglas Mayne