Mounting of Linux volumes

James Clawson jclawsonx at mac.com
Thu Dec 1 16:27:37 MST 2005


I will access the volume as root as you suggested.  As for the second  
disk, it was RAID 5, and your response was pretty much what I  
suspected.  Oh, well.

Thank you for your response.

Jim


On Dec 1, 2005, at 8:59 AM, Nicholas Leippe wrote:

> On Thursday 01 December 2005 04:12 am, James Clawson wrote:
>> Greetings to my fellow Linux users,
>> I need to mount two HDDs for data recovery purposes.  One is a disk
>> which contains three valid Linux partitions, and the other was once
>> part of a RAID which spanned three disks.
>>
>> The first HDD is in a computer which will boot, but for which I have
>> no username or password lists.  I can mount the partitions on that
>> disk while running Linux from a different HDD and, as root, change
>> the ownership and permissions of all of the files on that HDD, which
>> would allow me to recover the data I need from the drive.  The result
>> of this would be that that drive would no longer be a usable Linux
>> install.  As that result is not desirable, I intend to duplicate all
>> of those partitions using dd and then extract the data from the
>> duplicate volume.  Does anyone know of a better solution to this?
>>
>
> You shouldn't need to change the ownership and permissions to  
> access the files
> as root.  You can just mount it ro and get anything off from it  
> that you need
> without affecting the installation.  (Or just edit /etc/passwd and  
> boot it.)
>
>
>> I have retrieved a fair amount of data already from the second HDD by
>> use of foremost.  Thank you to those on the list who recommended that
>> application to me earlier this year.  Unfortunately, I have
>> encountered a problem using that tool, as the drive was fragmented,
>> and any file larger than a few blocks seems to be broken up due to
>> that fragmentation.  However, I believe I have repaired the surface
>> of the volume sufficiently such that where I able to reassemble the
>> RAID, I believe the disk, would be usable.  As the other two disks of
>> the RAID are not usable, that is not an option.  Is there any way to
>> access the raw files on that disk without the remainder of the RAID?
>> Is there any way to rebuild or reorder the segments to minimize the
>> impact of fragmentation on the volume?
>
> Depends on the raid level.
> raid 0, you're out of luck.  You've only got 1/3rd of the data you  
> need.
> raid 1, you're in luck, you can just treat the drive as a single  
> volume and
> continue your data recovery attempts.
> raid 5, you're out of luck,  You've only got 1/2 of the data you need.
>
> If it was raid 0 or raid 5, the 'fragmentation' you're seeing is  
> from the
> blocks of the files (in 'chunk' sizes specified when the md  
> partition is
> created) are distributed between the drives in the array--IOW not  
> all of the
> data was ever even on the drive.
>
> Additionally, if this is the case, any 'repairing' that includes  
> moving blocks
> around would make reassembling the array impossible as their  
> location is
> predefined by the array--the array would now be scrambled.
>
>
> -- 
> Respectfully,
>
> Nicholas Leippe
> Sales Team Automation, LLC
> 1335 West 1650 North, Suite C
> Springville, UT  84663 +1 801.853.4090
> http://www.salesteamautomation.com
>
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