Bob Bishop <[EMAIL PROTECTED]> wrote on 02/19/2006 01:27:05 PM: <snip> > >My problem is that the md5 hash of the image file is different from > >that of the original HD (acquired via the command: dd if=/dev/hdb > >conv=noerror,sync | md5sum > /mnt/hda7/orig_disk_md5sum.txt) [etc] > > You might need to specify obs=<something>. If dd uses different > output block sizes in the two cases the amount of padding in the last > block will be different and so will the digest. > Quite often, getting an older, digressing hard drive to match hashes is difficult even when writing two separate images back-to-back.
One thing we've noticed that has little to do with the age or health of the hard drive is that power issues can also cause a drive to image diffferently. Make sure your power source is fully powering the drive. In our case, we were using a USB write blocker to image laptop drives. Using the in-cable power did not sufficiently power the drives and we resorted to using an additional connection (provided on the write-blocker) to power the drive. Our image quality and consistency cleared up considerably after that.
