"Man-wai Chang ToDie (33.6k)" <toylet.toylet******.com> writes:

>> Do you mean in addition to the ECC done by the disk drive which works on
>> all the common file systems?

>Even those cheap consumer-grade hard disks have this ECC thing?

Oh yes, masses of it. It can correct huge native error rates. That is one
way they squeeze every last bit out of those drives.


>> If the data is really critical a read after write check by the
>> application is what is needed.
>> Be sure to flush the cache before the verify or you will just check the
>> contents of RAM and not what's on the disk.

>I meant both the data and the checksum are stored in the
>file system so that you don't need the original file
>to verify the correctness of the data after a copy
>process.

Do you want to just check it, or correct it as well. The latter is much
harder and more extensive in space.


>> What is the application?

>Nothing, just backing up data.

That is probably something in your backup program-- eg storing an MD4 sum
with every file of that file. Of course what do you do if the checksum says
the file is corrupted?