[gentoo-user] Re: "loopback mount" hard-drive image created with dd?

[Remy Blank]

Yahya Mohammad wrote:

# losetup /dev/loop0 /path/to/diskimage
# fdisk -l /dev/loop0
(example)
Disk /dev/sdb: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        1044     8385898+   c  W95 FAT32 (LBA)
/dev/sdb2            1045       19457   147902422+  83  Linux

Thanks for the tip! I didn't know you could mount a whole disk image as loopback, and see the partition table with fdisk. I always printed the partition table before making the disk image.

I second that, I'm curious to know if it works

(example)
# fdisk -lu /dev/loop0

Disk /dev/loop0: 10.0 GB, 10056130560 bytes
240 heads, 63 sectors/track, 1299 cylinders, total 19640880 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0xc1afc1af

      Device Boot      Start         End      Blocks   Id  System
/dev/loop0p1   *          63     4097519     2048728+   b  W95 FAT32
/dev/loop0p2         4097520     8195039     2048760    5  Extended
/dev/loop0p5         4097583     8195039     2048728+   b  W95 FAT32

It does, I have done it before, but there's a special case for the first partition of the disk. According to your output of fdisk, it is supposed to start at cylinder 1. However, if you run fdisk with the -u option (giving the positions and sizes in sectors), you get the following: That is, the first partition starts at sector 63, i.e. at an offset value of 63 * 512 = 32256.

oh, and make a backup just in case :)

And mount the filesystem read-only with the "ro" mount option.

-- Remy

signature.asc
Description: OpenPGP digital signature