Re: How can i read really 512 byte?

[Janos Haar]

----- Original Message ----- 
From: "Milton Miller" <miltonm@xxxxxxx>
To: "Janos Haar" <janos.haar@xxxxxxxxxxxx>
Cc: <linux-kernel@xxxxxxxxxxxxxxx>
Sent: Tuesday, September 30, 2008 4:50 PM
Subject: How can i read really 512 byte?


> 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?

Thanks,
Janos Haar
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