On Fri, 08 May 2015 13:40:01 -0400 The Wanderer <wande...@fastmail.fm> wrote:
> On 05/08/2015 at 01:20 PM, German wrote: > > > On Fri, 08 May 2015 12:10:38 -0400 Gary Dale <garyd...@torfree.net> > > wrote: > > > >> On 08/05/15 10:32 AM, German wrote: > >>> Hi list. Ok, now I have a spare 2TB USB drive where I can save > >>> .img file. Is that the right procedure? Do I have make a snapshot > >>> of failed drive and transfer it as a .img file to a spare drive, > >>> correct? R-studio for linux can display files of failed drive ( > >>> TestDisk coudn't do it ). So now I think I'll proceed. What is > >>> exact command to do it with ddrescue and what file system the > >>> spare drive has to be formated? Thank you very much! > >>> > >>> > >> You can try ddrescue if=/dev/sdb1 of=failed.img where /dev/sdb1 > >> would be the partition that you want to recover. > > > > Thanks, but some clarification is needed. Now I have two drives, > > failed and a spare. Both are 2TB in size. Failed drive probably has > > 1.6 TB data I'd like to recover. It has only one partition I > > suppose. > > That's bad. > > If the drive has only one partition, it probably has a single > filesystem taking up all of its space. > > When you create a ddrescue image from that partition, the new image > will take up _at least as much_ space as the original filesystem. > That's not the 1.6TB of "used" space; it's the full 2TB of "total" > space. (Plus however much space is taken up by the "index" file used > by ddrescue while doing its work.) > > That means that if your two 2TB drives are actually the same size, the > "good" one will not have enough space to store the image you need to > rescue from the "bad" one. Thanks Wanderer. So, I have no chances with two drives the same capacity? Would you advise to wait when I can get more capacity drive and only then to proceed as to save some head ache? Once again, thanks for such a complete instructions. > > > So, if failed drive is for instance /dev/sdb and spare drive is for > > isntance /dev/sdc, the right command will be ddrescue if=/dev/sdb > > of=/dev/sdc/failed.img ? > > No. > > With ddrescue, you do not (want to) create a new filesystem directly > on the new device. > > What you want to do is create a filesystem _image_, in a file which is > stored on the new device. > > Step-by-step, what you do is: > > * Create a filesystem on your "good" drive (/dev/sdc). You can use any > filesystem you want. > > * Mount the newly created filesystem somewhere. For example, if you > want to mount it to the empty directory '/mnt/new_disk', you could > run the command: > mount /dev/sdc1 /mnt/new_disk > > * Run the command > ddrescue /dev/sdb /mnt/new_disk/sdb_failed.img > /tmp/sdb_failed.ddrescuelog > Note that this will create _two_ files: the rescued filesystem image, > and a "log file" which ddrescue uses to keep track of what it has > already successfully rescued and where it has encountered errors. This > second file will take up additional space. > > * If you have enough free space, copy the resulting sdb_failed.img to > a separate location, so you have a backup copy if something goes > wrong. > > * Run recovery tools (starting with fsck, as Gary Dale suggested) on > sdb_failed.img, and see how much you can recover. > > * Mount sdb_failed.img, using a loopback mount, and copy out whatever > files you can to a new location. > > > Recovering data from a failed drive using ddrescue, dd_rescue, or > myrescue is entirely possible; I've done it myself. However, it is not > trivial, and in my experience the process requires considerably more > space than the size of whatever drive is being rescued. > > > > Personally, I would probably recommend the use of myrescue rather than > of ddrescue or dd_rescue, but any of them can work if you use them > right. > -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20150508141619.37003...@asterius.asterius.net
