Re: [Bug-ddrescue] Disk 2 Disk (Part Deux)

[andrew zajac]

Hi Al.

--- On Thu, 10/29/09, Marian Csontos <address@hidden> wrote:

Is this ext2 or ext3? Does not matter, as it would not work for either.
Your disks use 1KiB blocks, and according to
http://en.wikipedia.org/wiki/Ext2 max.allowed file size is 16GB :-(

No.  Ext3 uses 4096 byte blocks by default.  The theoretical max file size is 4TB.

Use tune2fs -l to list the attributes of your ext filesystem.

So, yes Al, you will be able to image that drive onto your linux partition.

> 1) When going disk to disk can you image both the whole drive and all its
> partitions or can you only go disk to disk on a partition by partition
> basis?
>   

You can do whatever you want.  On a practical level, it depends on what your problem is.

If the partition table of the bad drive is still intact and you can see the partitions on the drive, you can image a partition by itself.  Whether you image it to a file or directly to another drive is irrelevant.  However, if you are imaging a single partition, you probably want to image it to another partition and not to the whole destination drive.  So you would partition the target (destination) drive and image, say the bad drive's partition number one (sda1) to the destination drive's partition one (sdb1).  There would be little point in imaging sda1 to sdb (raw block device) if the destination drive is larger than the source (bad drive) since you will not be able to use that space.

You may just as well image it to a file on the partitioned and formatted destination drive.  That way, you don't have to repartition your destination drive.  You just create one filesystem and don't worry about the extra space  - it will still just be there one you are done.

If the partition table (first block) of the bad drive is unreadable, then you can't access any individual partitions - well, you can figure out where they are supposed to be and then just image that, but why bother?  It's just more straightforward to image the whole drive.  Again, you can image it to a file and then mount the partitions on the image file as loop devices or you can image the whole drive to another destination whole drive.

If you image the whole source (bad) drive to one partition on the destination drive, then, once you are done, you need to go through the process of mounting the partition as a loop device and using an offset since there is not supposed to be a partition table at the beginning of a partition.  I find it more straightforward to just image it as a file and go from there.

I just image everything to a file.  If (for kicks and giggles) I wanted to image directly to another drive, I would probably just do drive to drive (example: sda to sdb) or partition to partition (example sda2 to sdb1) depending on what I need.  Although you can do it, I don't see the point of imaging raw drive to partition (sda to sdb1) or partition to raw drive (sda1 to sdb) - there's fewer steps and less thinking/guessing involved in just imaging to file in those cases.

It's like jazz.  There's no wrong moves, just choices that are less appealing than others.

Cheers!

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