Re: Time spent waiting for uncorrectable errors

[Hans-Peter Jansen <hpj@urpla.net>]

On Monday 16 February 2004 09:21, Alex Goller wrote:
> Hi,
>
> is there any data regarding how long current disks try to read a
> sector before quitting with an uncorrectable error? The problem is,
> that i have no reliable way to reproduce the error, i will try to
> read from a hopefully (!) broken disk this afternoon and try to
> measure the time spent for that.

IIRC, the kernel tries to read a defect block exactly 8 times.

The problem is (according to some Maxtor guy), a drive, that returns
a hard sector error has tried to read it internally a few tausand
times (~2650), which results in about 21200 physical retries.

Unfortunately this renders an unpatched linux kernel useless for data 
recovery tasks. Well, not useless in general, but you simply need a 
_lot_ of patience.

Last time I've done it myself, it took about 40 hours to copy a 
defective 80 GB HD with dd_rescue. Fortunately, the damage was in
some mpeg2 streams, which is quite robust in handling long runs of
zeros ;-)..

Pete