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.
Can I try to run fsck on the failed 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).
>
>
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