[Beowulf] HD undetectable errors

Henning Fehrmann henning.fehrmann at aei.mpg.de
Mon Aug 24 04:58:56 EDT 2009

Hello Peter,

Thank you for the answer.

> Yes. But most wont and it will hur quite a lot performance wise. I know, for 
> example, that our IBM DS4700 with updated firmware can 
> enable "verify-on-read".

Is it easily possible to switch this feature on and off?
E.g., one does a a test from time to time but for the every day usage
one avoids "verify-on-read"?

> Remember that you have to calculate this against the amount of corrupt data, 
> not the total amount of data.

My hope is that corrupted data will be repaired by the RAID controller. The
chance to loose the data on a RAID6 system is of the third order should be very small.
My guess it that the silent corruption rate is higher if the RAID
system does not have the "verify-on-read" feature. I try to get the numbers. 
I assume in this calculation that no bit flips occur on the buses or
the controller which is already sort of naive.

Thank you.

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