Re: Help with ddrescue
On Fri, 08 May 2015 16:00:05 -0400
Gary Dale <garydale@torfree.net> wrote:
> On 08/05/15 02:56 PM, German wrote:
> > On Fri, 08 May 2015 14:48:47 -0400
> > Gary Dale <garydale@torfree.net> wrote:
> >
> >> On 08/05/15 02:32 PM, German wrote:
> >>> On Fri, 08 May 2015 14:23:39 -0400
> >>> The Wanderer <wanderer@fastmail.fm> wrote:
> >>>
> >>>> On 05/08/2015 at 02:16 PM, German wrote:
> >>>>
> >>>>> On Fri, 08 May 2015 13:40:01 -0400 The Wanderer
> >>>>> <wanderer@fastmail.fm> wrote:
> >>>>>
> >>>>>> On 05/08/2015 at 01:20 PM, German wrote:
> >>>>>>> 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?
> >>>> Yes, that's what I'd do in your situation. A 2.5TB drive should
> >>>> be more than enough; that would also let you store the
> >>>> sdb_failed.ddrescuelog file on the same drive, if you need to, so
> >>>> you don't have to worry about finding space for it elsewhere.
> >>>>
> >>>>> Once again, thanks for such a complete instructions.
> >>>> I wouldn't call the directions I gave "complete"; there's a lot
> >>>> of details you'll still have to work out on your own, because
> >>>> they will depend on the exact details of your failure and the
> >>>> recovery process. Still, they should at least provide you a good
> >>>> starting point.
> >>>>
> >>>> Again, I would recommend that you install (and read the
> >>>> documentation for) myrescue, and consider using that instead of
> >>>> ddrescue. I've used both (as well as dd_rescue), but if memory
> >>>> serves I've had better results with myrescue.
> >>>>
> >>> Thanks so much. I wait when I can get a bigger drive. Have a
> >>> greatest day!
> >>>
> >>>
> >> I think Wanderer may be overstating the problem a little. If the
> >> two drives are exactly the same size, you can use ddrescue to
> >> duplicate the failed drive onto the new drive (ddrescue if=/dev/sdb
> >> of=/dev/sdc). However this will limit you to recovering in place on
> >> new drive.
> > What will this duplication accomplish? What advantages if I am
> > duplicate? After I duplicate the drive, what are my next steps?
> With the drive duplicated, run fsck on the new drive. Hopefully the
> file system will be repairable. If it isn't, you can run testdisk or
> whatever to try to rescue files to another device (not the original,
> bad drive).
>
>
What will happen when I duplicate drive? Why is that failed drive is
failed and duplicated drive might be repairable? If it's duplicated, it
will be exactly the same, no? Confused. And bad drive is physically ok
I think, it is just something wrong with file system. MTF?
Reply to: