Re: How can i read really 512 byte?

[Milton Miller]

On Oct 1, 2008, at 5:23 AM, Janos Haar wrote:

> > On Tue, 30 Sep 2008 at 08:29:15 -0400 (EDT), Janos Haar wrote:
> > > Now i am working on recover some data from one defective drive.  I
> > > am using dd_rescue, and dd, but both ready only 4K, i think, because
> > > the kernel's block size is 4K.
> > > I have tried to google for the solution, but only found this trick:
> > > losetup /dev/loop0 /dev/hdc
> > > blockdev --setbsz 512 /dev/hdc
> > > and after this set, trying to read the hdc...
> > > It looks like working on the first look, but not really. :-( The
> > > 512 size bad sectors still have 4K sizes, but the reading attempt
> > > takes more (8x ?) longer.
> > > Somebody can help me to set the reading block size to 512 byte?
> > You need to add O_DIRECT to the open call in the flags parameter
> > (the second argument).   (My brother tested this a year or so ago,
> > and it worked for him).
> > milton
>
> Hello,
>
> Thank you for the information.
> Can you help me a little bit more?
> Where need to add this parameter?
> In the kernel, in the blocked's source, or in the dd_rescue's source?

dd_rescue ... there is a call to open, add O_DIRECT to the second 
argument and recompile.  If it says unknown identifier, just copy the 
#define from the kernel header into the dd_rescue source.

milton

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/