Messages in this thread | | | Subject | Re: Blockbusting news, this is important (Re: Why are bad disk sectors numbered strangely, and what happens to them?) | From | Krzysztof Halasa <> | Date | 17 Oct 2003 13:24:10 +0200 |
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John Bradford <john@grabjohn.com> writes:
> Besides, are you positive that you always got the correct data off the > disk? See the discussions about hashing algorithms - maybe the drive > simply returned data that had an additional bit flipped and wasn't > identified as bad.
One bit? No chance. The same as with ECC RAM - one bit error will always be detected.
> If you are having to try over 1000 times from > userspace, the drive is in a bad way. You shouldn't really make > assumptions that you do usually, (that the error correction is good > enough to ensure bad data isn't returned as good data). If you are > recovering data from a spreadsheet, for example, the errors could go > unnoticed, but have catastrophic results.
Then you have to abandon using any hard drivers. Or computers at all. Well, mirrors (with read-and-compare) are probably good enough for you, but it has to be done at application level.
> Of course you will - it's remapped, the data isn't overwritten! You > may need more advanced tools,
= in practice, it's lost. Have you seen such tools?
> but you can still seek the heads to that > part of the platter and get data from the head-amp. Just because you > couldn't use your simple method anymore is real reason to argue > against fixing the problem.
against _changing_ the problem (it doesn't go away), breaking things which are now sane.
> This may be more sensible, but not for the reasons you are suggesting, > and not in the way that you are suggesting.
Then note that a drive can be temporarily unable to read most of the data - due to, say, incorrect supply voltage or very high level of electromagnetic interferences.
Would you like to trash _all_ your data in such case automatically?
> Suspect drive? Bin it. Do you really not value your data enough to > do that?
Do you really not value your data enough to mark it as inaccessible?
If it comes to non-standard recovery then you should rather go for backups. -- Krzysztof Halasa, B*FH - 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/
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