[Beowulf] instances where a failed storage block is not all zero?

Eric W. Biederman ebiederm at xmission.com
Wed Jul 7 23:12:53 EDT 2010

"David Mathog" <mathog at caltech.edu> writes:

> With "modern" hardware are there currently any notable instances where a
> failed read of a hardware storage area block results in that missing
> data being filled in with something other than null bytes?   For
> instance, if a disk swapped a bad block out of the inside of a file, or
> a region of a DVD goes bad.  (Assuming that the software reading it can
> even go on beyond the failure, which is often not possible, for instance
> on many tapes.)  

I seem to remember people looking at the expected failure rates were saying
that were are getting close to the point where a single pass through the
disk will have a single undetected bit flip.  Which is one of the reasons
disk manufacturers have wanted to go to 4K blocks recently so the can get
more error checking/correcting per bit.

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