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[OM] Re: HP PC troubles - hard disk errors

Subject: [OM] Re: HP PC troubles - hard disk errors
From: Manuel Viet <oly@xxxxxxxxxx>
Date: Tue, 19 Feb 2008 13:14:04 +0100
Le mardi 19 Février 2008 12:14, Marc Lawrence a écrit :

> No, they're not. They're fine. The way I understood the CRC cyclic
> redundancy check (CRC) message, it indicates the hard disk has a problem
> where the file sits rather than the file itself having any internal
> corruption [...]

You're right because your problem is certainly mechanical.

> The chkdsk completed with the indicated problems, and files removed.
> There weren't all that many (about ten image files, plus a few other
> things including mention of registry files - I haven't looked properly
> yet) but the files were removed, unrecoverable, from the hard disk by
> chkdsk.

[pedantic minute] (As you had proper backups, you are not really concerned but 
I write that for the benefit of the lazys [is it lazies ?] among us). In case 
of a hardware fault, chkdsk is most likely to worsen the disk condition. 
Modern disks are intelligent devices. They have about 10% of their capacity 
in spare sectors where they copy by themselves weak sectors, then they mark 
the old sectors bad internally and just silently correct errors until there's 
no more spare sectors to allocate. So, when the corruption spreads, it's a 
good sign the device has already exhausted its safety ressources. chkdsk goes 
over the whole disk looking for logical faults, and will tax the already 
damaged device to the maximum, which can lead to a sudden complete failure. 
So in case some random files are corrupted, if you have no backups (Booo !!! 
Bad !!!), it's high time to *stop any undue activity* and *backup what you 
can while you still can*. In that case chkdsk will at best be a plaster on a 
wooden leg, at worse...

Modern disks have a feature called SMART you can use to check your disk 
condition. You need a software to access SMART data, but I don't do windows 
so I can't give you a specific name. Maybe something called aida can do it, I 
don't really know (aida collects various informations about your computer). 
SMART will tell you things like the number of time your HD has been powered 
up, the number of relocated sectors, the number of corrected crc errors, the 
number of uncorrected errors, the maximum temperature your disk has been 
exposed to, etc. Used on a regular basis, SMART will help you decide when 
your disk is too weak to be trusted before it shows any other sign of 
failure. (Then again, don't interpret crc corrections as a dooming sign. 
While those errors are evenly scattered among the disk, it's just a normal 
side effect of the techonological feat that allows you to pack megabytes of 
data on a square inch. There's a lot of magic going on inside and crc is part 
of this magic.) 


-- 
Manuel Viet

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