Bad Block

[guru.naveen]

Hi,

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

Thanks

Guru

 

[Pegasus \(MVP\)]

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.

 

[Rian Wisandanu]

I think is both write and read.

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

 

[guru]

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

 

[Joep]

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.

 

[Pegasus \(MVP\)]

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.

 

[Joep]

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.

 

[Pegasus \(MVP\)]

It's a tad more complicated than that.


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.

You're right, of course.

 

[guru]

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