Can I abuse md like this?

Can I abuse md like this?

[Bill Davidsen]

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.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

Re: Can I abuse md like this?

[Neil Brown]

On Saturday December 23, davidsen@tmr.com 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.
> 
> 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

Re: Can I abuse md like this?

[Bill Davidsen]

Neil Brown wrote:
> On Saturday December 23, davidsen@tmr.com 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.
>>
>> 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.
> 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.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979

Re: Can I abuse md like this?

[Bill Davidsen]

Bill Davidsen wrote:
> Neil Brown wrote:
>> On Saturday December 23, davidsen@tmr.com 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.
>>>
>>> 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.
>> 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.

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979