[CentOS] puzzling md error ?

On Sun, Feb 28, 2010 at 02:37:13PM -0800, John R Pierce wrote:
> And how do I know all these mirror data mismatches are Swap?  does not 
> each mismatch mean the mirrors disagree, which means one of them is 
> wrong.  Which one?  since they aren't timestamped or checksummed (like 

This thread is very timely.  I updated my C5.3 to 5.4 last week (not
sure why it took me so long) and this morning noticed my raid5 was
resyncing.  5*1Tbyte disks.  The resync took...
  Feb 28 04:22:02 mercury kernel: md: syncing RAID array md3
  Feb 28 16:27:06 mercury kernel: md: md3: sync done.

Performance was bad during this time.  Not terrible from an interactive
point of view, but a job that normally run from 4am to 10am didn't finish
until 3pm.

I like the concept of checking the disks are good, but it really
sounds like there are practical problems (false positives, performance
degregation) .

So I think /etc/sysconfig/raid-check is going to read
  ENABLED=no

-- 

rgds
Stephen