[CentOS] Using CentOS 7 to attempt recovery of failed disk

Sat Sep 26 20:30:13 UTC 2020
Erick Perez - Quadrian Enterprises <eperez at quadrianweb.com>

I will suggest using dmesg -w to monitor during dd the sector numbers that
fail in order to skip them.

Also, perhaps the timeout of each read error is killing you (default 30
seconds) and you may have thousands.

On linux, /sys/block/<deviceName>/device/timeout (such as
/sys/block/sda/device/timeout) is the timeout setting in seconds, which
currently defaults to 30.

As root, echo 1 > /sys/block/<deviceName>/device/timeout will change the
timeout to 1 second.

Perhaps this will help you achieve a DD without waiting for the read
timeouts.

Erick.





On Sat, Sep 26, 2020, 2:27 PM Fred <fred.fredex at gmail.com> wrote:

> Well, I'm not a noted expert on ddrescue, but my limited experience tells
> me that when it hits bad spots (or a big cluster of them) it can go very
> slowly as it tries multiple times to read each sector (or track, I'm not
> sure which, in this case). It keeps a list of bad spots and goes back at
> the end to try again to read something from them. Of course, if you've had,
> eg. a head crash, there's probably nothing there to read.
>
> On Sat, Sep 26, 2020 at 1:41 PM Jerry Geis <jerry.geis at gmail.com> wrote:
>
> > Hello
> >
> > I did try the "dd conv=noerror …"
> > The ddrescue - doesnt stop - it just doesnt "continue" past a certain
> > point. Somewhere around the 117G mark - it just doesnt go past that .
> > (same with dd, gets to 117G and just doesnt continue.
> > I have let the dd run all night - did not go past the 117G.
> >
> > Thanks for any suggestions.
> >
> > Jerry
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