[Nottingham] HDD bit flips: Anyone seen this before?!

[Martin]

Martin wrote:
> Martin Garton wrote:
>> On Wed, 2005-07-27 at 21:56 +0100, Martin wrote:
>>
>>> Nearly 200 files give a failed comparison. Looking at two of them, 
>>> they have just one bit that has been flipped (md5sum and then cmp to 
>>> look).
>>
>> Are these bits at seemingly random positions in the files or is there
>> any apparent pattern?  It is always exactly one bit? And is the bit
>> always in the same position within a byte or word or anything like that?
> 
> Multimegabyte files---, and the ones I've checked (ok, very bad 
> pun) have always been the lsbit and somewhere mid-file.

OK, I've updated the backups using rsync, and then compared using brute 
force "tar -d" and:

Doing this four times in both directions and all files check out OK 
byte-for-byte for all 200GBytes or so. (OK, so it did take a very long 
time...)

So, "I don't know"!


One thing learnt from all this:

'Tis a Very Good Idea to have more than just /one/ backup to compare with!


Good luck,
Martin

-- 
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Martin Lomas
martin at ml1.co.uk
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