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    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.


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