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Can I abuse md like this?

DISCUSSION Bill Davidsen 2 participants 4 messages Dec 24, 2006 – Dec 30, 2006 MD RAID

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#0 lore raw

I hope I can use the md code to solve a problem, although in a way probably not envisioned by the author(s).

I have a disk image, a physical dump of every sector from start to finish, including the partition table. What I hope I can do is to create a one drive RAID-1 partitionable array, and then access it with fdisk or similar. These partitions are not "nice" types such as FAT, VFAT, ext2, etc, this is an odd disk, and I "saved it" by saving everything. Now I'd like to start dismembering the information and putting it into useful pieces. I even dare to hope that I could get the original software running on a virtual machine at some point.

The other alternative is to loopback mount it, I'm somewhat reluctant to do that if I can avoid it.

Yes, the partition table is standard in format if not in content.

Signature · 3 lines
bill davidsen <[email protected]>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979
#1 lore raw
Quoted 12 lines · On Saturday December 23, [email protected] wrote:

I hope I can use the md code to solve a problem, although in a way probably not envisioned by the author(s).

I have a disk image, a physical dump of every sector from start to finish, including the partition table. What I hope I can do is to create a one drive RAID-1 partitionable array, and then access it with fdisk or similar. These partitions are not "nice" types such as FAT, VFAT, ext2, etc, this is an odd disk, and I "saved it" by saving everything. Now I'd like to start dismembering the information and putting it into useful pieces. I even dare to hope that I could get the original software running on a virtual machine at some point.

Quoted 4 lines

The other alternative is to loopback mount it, I'm somewhat reluctant to do that if I can avoid it.

Yes, the partition table is standard in format if not in content.

Maybe...
Is this image in a file?
md only works with block devices, so you would need to use the 'loop' driver to create a block-device "/dev/loopX".

But as loop devices cannot be partitioned, you could then
mdadm -Bf /dev/md/d9 -amdp8 -l1 -f -n1 /dev/loopX

and then look at the partitions in /dev/md/d9_*

Should work.

NeilBrown

#2 lore raw
Quoted 8 lines · Neil Brown
Quoted 6 lines · On Saturday December 23, [email protected] wrote:

I hope I can use the md code to solve a problem, although in a way probably not envisioned by the author(s).

I have a disk image, a physical dump of every sector from start to finish, including the partition table. What I hope I can do is to create a one drive RAID-1 partitionable array, and then access it with fdisk or similar. These partitions are not "nice" types such as FAT, VFAT, ext2, etc, this is an odd disk, and I "saved it" by saving everything. Now I'd like to start dismembering the information and putting it into useful pieces. I even dare to hope that I could get the original software running on a virtual machine at some point.

The other alternative is to loopback mount it, I'm somewhat reluctant to do that if I can avoid it.

Quoted 8 lines
Quoted 2 lines

Yes, the partition table is standard in format if not in content.

Maybe...
Is this image in a file?
md only works with block devices, so you would need to use the 'loop' driver to create a block-device "/dev/loopX".

I was thinking nbd, actually.

Quoted 6 lines

But as loop devices cannot be partitioned, you could then
mdadm -Bf /dev/md/d9 -amdp8 -l1 -f -n1 /dev/loopX

and then look at the partitions in /dev/md/d9_*

Should work.

Sounds worth a try. Will be a learning experience if nothing else.

Signature · 3 lines
bill davidsen <[email protected]>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979
#3 lore raw
Quoted 17 lines · Bill Davidsen
Quoted 8 lines · Neil Brown
Quoted 6 lines · On Saturday December 23, [email protected] wrote:

I hope I can use the md code to solve a problem, although in a way probably not envisioned by the author(s).

I have a disk image, a physical dump of every sector from start to finish, including the partition table. What I hope I can do is to create a one drive RAID-1 partitionable array, and then access it with fdisk or similar. These partitions are not "nice" types such as FAT, VFAT, ext2, etc, this is an odd disk, and I "saved it" by saving everything. Now I'd like to start dismembering the information and putting it into useful pieces. I even dare to hope that I could get the original software running on a virtual machine at some point.

The other alternative is to loopback mount it, I'm somewhat reluctant to do that if I can avoid it.

Quoted 8 lines
Quoted 2 lines

Yes, the partition table is standard in format if not in content.

Maybe...
Is this image in a file?
md only works with block devices, so you would need to use the 'loop' driver to create a block-device "/dev/loopX".

Quoted 8 lines

I was thinking nbd, actually.

Quoted 5 lines

But as loop devices cannot be partitioned, you could then
mdadm -Bf /dev/md/d9 -amdp8 -l1 -f -n1 /dev/loopX and then look at the partitions in /dev/md/d9_*

Should work.

Sounds worth a try. Will be a learning experience if nothing else.

Rather than setup nbd I did try a loop mount, and the whole process worked flawlessly. I was able to look at partitions, read the partition table, and generally do anything I could from a device. It worked so well I backed it up as an image, just in case I ever want to do something else with it.

Many thanks.

Signature · 3 lines
bill davidsen <[email protected]>
 CTO TMR Associates, Inc
 Doing interesting things with small computers since 1979