[lkml]   [2003]   [Oct]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: Blockbusting news, this is important (Re: Why are bad disk sectors numbered strangely, and what happens to them?)
Norman Diamond wrote:

>Replying first to Hans Reiser; below to Russell King and Pavel Machek.
>>Instead of recording the bad blocks, just write to them.
>If writes are guaranteed to force reallocations then this is potentially
>part of a solution.
>I still remain suspicious because the first failed read was milliseconds or
>minutes after the preceding write. I think the odds are very high that the
>sector was already bad at the time of the write but reallocation did not
>occur. It is possible but I think very unlikely that the sector was
>reallocated to a different physical sector which went bad milliseconds after
>being written after reallocation, and equally unlikely that the sector
>wasn't reallocated because it really hadn't been bad but went bad
>milliseconds later. In other words, I think it is overwhelmingly likely
>that the write failed but was not detected as such and did not result in
perform the write after the failed read, that way the drive knows it is
a bad block at the time you write.

>Now, maybe there is a technique to force it anyway. When a partition is
>newly created and is being formatted with the intention of writing data a
>few minutes later, do writes that "should" have a better chance of being
>detected. The way to start this is to simply write every block, but this is
>obviously insufficient because my block did get written shortly after the
>partition was formatted and that write didn't cause the block to be
>reallocated. So in addition to simply writing every block, also read every
>block. For each read that fails, proceed to do another write which "should"
>force reallocation.
>Mr. Reiser, when I created a partition of your design, that technique was
>not offered. Why? And will it soon start being offered?
I think I discussed with Vitaly offering users the option of writing,
reading, and then writing again, every block before mkreiserfs. I
forget what happened to that idea, Vitaly?

>Also, I remain highly suspicious that for each read that fails, when the
>formatting program proceeds to do another write which "should" force
>reallocation, the drive might not do it.
I am not going to worry about such suspicions without evidence or drive
manufacturer comment, as it has not been our experience so far.

>Why does it matter? The drive already reported a read failure. Maybe Linux
>programs aren't all smart enough to inform the user when a read operation
>results in an I/O error, but drivers could be smarter.
There is a general problem with reporting urgent kernel messages to
users thanks to GUIs covering over the console.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:58    [W:0.056 / U:0.308 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site