On Wed, 20 Jan 2010 17:43:45 -0500, Brett Russ [off-list ref] wrote:

On 01/20/2010 05:30 PM, Majed B. wrote:

quoted

He needs to run a full offline or long test before checking with
smartctl -a -- since it won't show any sector errors if those tests
weren't run at least once.

Not sure I agree with that.  The md checks he's been doing will cause a 
read of all data regions of the relevant partition and if the disk is 
throwing errors, those sectors should be marked probational.  Then, if a

subsequent repair ends up remapping them, those sectors will show up as 
remapped.

The grep will show both probational and remapped sector counts for each 
drive.

BTW, the cmd should also include an echo so it's easy to tell which 
drive is being reported:

for di in a b c d e f g; do echo $di; smartctl -a /dev/sd$di | grep -i 
_sect; done

Interestingly enough, I'm struggling with a system on this matter too... I
can never seem to get rid of mismatches.

# for di in a b c d e f g; do echo $di; smartctl -a /dev/hd$di | grep -i
sect; done
a
=== START OF INFORMATION SECTION ===
=== START OF READ SMART DATA SECTION ===
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always  
   -       0
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always  
   -       0
b
c
=== START OF INFORMATION SECTION ===
=== START OF READ SMART DATA SECTION ===
  5 Reallocated_Sector_Ct   0x0033   100   100   036    Pre-fail  Always  
   -       0
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always  
   -       0

Full offline tests of both drives less than 400 power on hours ago all
came up clean. No read errors. Just mismatches.

I can run a repair on them and STILL have mismatches again after a check.
At the moment:

# cat /sys/block/md2/md/mismatch_cnt
1024

It's in the middle of a repair now - as quite often the filesystem on
/dev/md2 will go read-only due to a journal error. I've tried everything
except replacing hardware to figure out what's going on here - but it will
do this like clockwork every month. A reboot later and it'll run an fsck,
find no errors, then between 21 and 30 days later it will go readonly
again.

It's annoying as hell and I wish I could get to the bottom of it!

-- 
Steven Haigh
 
Email: netwiz@crc.id.au
Web: http://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299