Dear Chris,

In message [ref] you wrote:

quoted

Correct, these are 3 different machines.

Too bad. Better to test first, than commit so many computers and arrays
for such a major change.

In hindsight you are of course correct.  But then, these are still not
really vitally critically systems, and I hve to admit that I did not
expect such kind of problems.  I have installed a large number of
Fedora releases before (all of them since FC4 actually, on quite a
number of systems), and while there have always been some problems, I
never ran into something like this before.

Unclear. If parity chunks are both wrong, then that means you
effectively have partial RAID 0 depending on what parity chunks are
correct or not. I'm not recommending this, but if you set one disk to
faulty and started your file system and file tests again

 if they're

bad then indeed it's parity that's affected. If you don't get errors,
then it indicates the test method is insufficient to locate the errors
and it could still be data that's affected.

OK, I will keep this in mind. If needed, I can dedicate one of the
systems to even a destructive test without too much actual loss.

It's a tenuous situation. It might be wise to pick a low priority
computer for regression, and hopefully the problem gets better rather
than worse. If the assumption is that the parity is bad, it needs to be
recalculated with repair. If that goes well with tests and another check
scrub, then it's better to get on with additional regressions sooner
than later. Again in the meantime if you lost a drive, it could be a
real mess if the raid starts to rebuild bad data from parity. Or even
starts to write user data incorrectly too.

Well, I did this - the repair worked without errors, but it left again
a huge mismatch_cnt; raid6check on this array has not found any
problems so far - even though I see mismatch_cnt = 362731480

Best regards,

Wolfgang Denk

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