Re: detection/correction of corruption with raid6

[Redeeman <redeeman@metanurb.dk>]

On Fri, 2008-12-05 at 16:09 -0500, Justin Piszcz wrote:
> 
> On Fri, 5 Dec 2008, Redeeman wrote:
> 
> > On Fri, 2008-12-05 at 16:02 -0500, Justin Piszcz wrote:
> >>
> >> On Fri, 5 Dec 2008, Redeeman wrote:
> >>
> >>> Hello.
> >>>
> >>> I was looking at the PDFs linked to from the wiki, and found this:
> >>> http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf
> >>>
> >>> More specifically, section 4, starting on page 8.
> >>>
> >>> Am I understanding this correctly, in that with raid6, linux is capable
> >>> of detecting if the content on 1 disk is corrupted, and reconstruct it
> >>> from the remaining disks?
> >>
> >> I ran md/raid6 for awhile, do you mean remap the bad sector on the fly?
> >> Linux/md raid does not do this afaik.
> >
> > No, i mean, if one disk does silent corruption
> 
> What would the error look like?  Both md/Linux & in the 3ware manual 
> recommend you run a 'check' across the raid at least once a week 
> (3ware/raid-verify) and md/Linux in Debian runs a check once a month I 
> believe to eliminate these issues.
> 
> If you are asking whether a read error of a latent sector from the one 
> disk will result it reading the data from the second disk that is a good
> question.

im asking, if one disk in a raid6 setup suddenly decides to flip a few
bits in some bytes, will it be able to detect that in a scan, and
correct it? i cant see how it can do it on raid5, but maybe raid6?
> 
> Justin.
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