Hi,

How the Scan utilities detect Bad Blocks. On what Criteria, it will
tell that particular block is a bad block.

Thanks

Guru

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi,
>
> How the Scan utilities detect Bad Blocks. On what Criteria, it will
> tell that particular block is a bad block.
>
> Thanks
>
> Guru
>

A block is bad when the disk subsystem is unable to
read a cluster. Run chkdsk /f /r from the Command Prompt.

I think is both write and read.


"Pegasus (MVP)" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> Hi,
>>
>> How the Scan utilities detect Bad Blocks. On what Criteria, it will
>> tell that particular block is a bad block.
>>
>> Thanks
>>
>> Guru
>>
>
> A block is bad when the disk subsystem is unable to
> read a cluster. Run chkdsk /f /r from the Command Prompt.
>
>

hi,

also what I want is what exactly mean ' unable to read' -

How it will decide that it is not able to read.

Whether it will -- cross check with previously written ECC with the
currently existing data.
if it doesn't match then it is read error or bad block ??

Regards

Guru

"guru" <(E-Mail Removed)> wrote in message
>
> Whether it will -- cross check with previously written ECC with the
> currently existing data.
> if it doesn't match then it is read error or bad block ??

Hi

Google for 'ATA command set' to learn what disks themselves do before a
read/write error is reported. Indeed ECC is one means of verifying and even
correcting data.

--
Joep

"guru" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> hi,
>
> also what I want is what exactly mean ' unable to read' -
>
> How it will decide that it is not able to read.
>
> Whether it will -- cross check with previously written ECC with the
> currently existing data.
> if it doesn't match then it is read error or bad block ??
>
> Regards
>
> Guru
>

All data read from memory or from bulk storage medium
goes through a CRC check (Cyclic Redundancy Check).
This check allows the operating system to detect read
errors in much the same way as you can detect spelling
errors in an English word. It is also possible that the read
head does not get a "0" or "1" of sufficient signal strength.

"Pegasus (MVP)" <(E-Mail Removed)> wrote in message
news:eb8$(E-Mail Removed)...
>
> All data read from memory or from bulk storage medium
> goes through a CRC check (Cyclic Redundancy Check).

It's a tad more complicated than that.

> This check allows the operating system to detect read
> errors in much the same way as you can detect spelling
> errors in an English word.

Not at all like that. It's not the OS that determines if data was read
correctly, it is the disk itself. On error the disk will report an error to
the OS.

--
Joep

"Joep" <(E-Mail Removed)> wrote in message
news:24bfb$4473017d$3eddca68$(E-Mail Removed)...
> "Pegasus (MVP)" <(E-Mail Removed)> wrote in message
> news:eb8$(E-Mail Removed)...
> >
> > All data read from memory or from bulk storage medium
> > goes through a CRC check (Cyclic Redundancy Check).
>
> It's a tad more complicated than that.
>
> > This check allows the operating system to detect read
> > errors in much the same way as you can detect spelling
> > errors in an English word.
>
> Not at all like that. It's not the OS that determines if data was read
> correctly, it is the disk itself. On error the disk will report an error
to
> the OS.
>
> --
> Joep
>
>

You're right, of course.

Hi,
Thanks for the info.

so after detecting bad sector, the disk report an error to the OS.
Where that Bad sector info will be stored : whether by the OS or in
disk itself. ?

-
Guru