Re: Linux 2.6.3-rc3 - IDE DMA errors on Thinkpad A30

[Bill Davidsen <davidsen@tmr.com>]

Jeff Garzik wrote:
> Valdis.Kletnieks@vt.edu wrote:
> 
>> On Sun, 15 Feb 2004 22:47:37 EST, Jeff Garzik said:
>>
>>> One for the todo list, I suppose...  a useable workaround for this is 
>>> probably good ole 'e2fsck -c', i.e. badblocks...  That says "check 
>>> again to see if this sector is bad", and -hopefully- will unmark bad 
>>> blocks that were incorrectly marked bad.
>>
>>
>>
>> Does e2fsck/badblocks issue the right ioctls/etc to make the disk read 
>> the
>> *original* block, or will the disk simply check the *redirected* block?
> 
> 
> 
> I'm not sure your question has meaning.
> 
> Consider:  ext2 reads sector 1234.  drive returns "media error", and 
> then swaps the bad sector for a good one.  Reboot and run badblocks. 
> badblocks reads sector 1234, in whatever manner the drive chooses to 
> present sector 1234 to the OS.

That's the point, the original 1234 may not really be bad.
> 
> "original" versus "redirected" block is invisible to the OS.  The OS 
> only knows that an event occured at a single point in time -- the media 
> error.

It's invisible unlesss the o/s chooses to see. By default there would 
never be an attempt to recheck the original sector 1234 unless the o/s 
tells the drive to do so. It may be that a write to the sector will work 
and there is nothing wrong with the sector (transient errors could be 
caused by mechanical or electrical transients, more likely in a laptop).

-- 
bill davidsen <davidsen@tmr.com>
   CTO TMR Associates, Inc
   Doing interesting things with small computers since 1979