Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 17 Oct 2003 12:51:13 +0100 | From | John Bradford <> | Subject | Re: Blockbusting news, this is important (Re: Why are bad disk sectors numbered strangely, and what happens to them?) |
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> Well, consider the two extremes we've seen in this thread now. Mr. Bradford > felt that the entire drive should be discarded on account of having one bad > block.
Please don't spread blatently mis-leading information.
My position on this is that if a drive is _persistantly_ unable to _write_ to any LBA address, it should be binned. Read errors are a separate concern. If they occur, the drive should simply return an error. The OS needs to do _NOTHING_. No special re-writing to force a re-allocation should be done - we assume the drive is going to do that, and if it doesn't:
1. DRIVE -> BIN
2. Restore backup.
> Mr. Machek feels that we should preserve the possibility of reusing > the bad block because in the future it might appear not to be bad. I take > the middle road. The drive should not be discarded until errors become more > frequent or numerous, but known bad blocks should be acted on so that those > physical blocks should not have a chance of being used again.
You may consider that a responsible attitude towards people who are paying for consultancy, and value their data at more than the physical cost of the disk, but I do not.
> Suppose the block became readable when the temperature drops (this one > didn't but I believe some can). What happens when the block becomes > readable, and then a program writes new data to that block, and the block > temporarily appears good? At that time it will get written and will not get > reallocated, right? And a few milliseconds later, what? I do not want that > block reused. I want it reallocated.
1. Monitor drive.
2. Out of spec temperature? If yes, remount R/O and page an operator.
3. Go to 1
> And when a drive doesn't guarantee reallocation, I want the driver to remove > the sector from the file system.
Such drives are no better in this regard than ST-506 drives in my opinion. I have almost always started discussions with a phrase such as, "assuming we are talking about modern drives that do their own defect management".
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