[nSLUG] Multiply-claimed blocks?

Dop Ganger nslug at fop.ns.ca
Wed Aug 31 14:26:35 ADT 2011


On Wed, 31 Aug 2011, Daniel Morrison wrote:

> On 31 August 2011 14:12, Dop Ganger <nslug at fop.ns.ca> wrote:
>> I also vaguely recall hearing about a prof who ran a daily md5 of all 
>> the files in his ~, and regularly found checksum errors.
>
> Sounds to me like that prof had a bad hard drive (or maybe his
> computer was at a high altitude?)

This was a shared computer. He did it because everyone else believe the 
system was perfect as long as there was no error, and he believed there 
wree intermittent errors coming through. I think he was seeing an error 
every month or so.

> At my old job, for many years, all system files on some dozens of
> machines were checksummed nightly, and any discrepancy had to be
> explained. There were no (or so few as to be negligible) occurrences
> of spontaneous changes.

Few != none.

I suspect this is a problem that won't be seen in a system that's 
protected by ECC or similar all the way through, but the system I'm 
talking about was a shared system for departmental use - I think an 
Ultrasparc of some description.

Cheers... Dop.



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