Messages in this thread | | | Date | Fri, 17 Oct 2003 15:45:10 +0400 | From | Hans Reiser <> | Subject | Re: 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 >reallocation. > > 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.
-- Hans
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |