Infrastructure/SOP/Raid Mismatch Count

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What to do when a raid device has a mismatch count
 
  
== Contact Information ==
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This SOP has moved to the fedora Infrastructure SOP git repo. Please see the current document at: http://infrastructure.fedoraproject.org/infra/docs/infra-raidmismatch.txt
Owner: Fedora Infrastructure Team
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Contact: #fedora-admin, sysadmin-main
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For changes, questions or comments, please contact anyone in the Fedora Infrastructure team.
  
Location: All
 
 
Servers: Physical hosts
 
 
Purpose: Provides database connection to many of our apps.
 
 
== Description ==
 
 
In some situations a raid device may indicate there is a count mismatch as listed in:
 
 
<pre>
 
/sys/block/mdX/md/mismatch_cnt
 
</pre>
 
 
Anything other than 0 is considered not good.  Though if the number is low it's probably nothing to worry about.  To correct this situation try the directions below
 
 
== Correction ==
 
 
More than anything these steps are to A) Verify there is no problem and B) make the error go away.  If step 1 and step 2 don't correct the problems, <b>PROCEED WITH CAUTION</b>.  The steps below, however, should be relatively safe.
 
 
=== Step 1 ===
 
 
Issue a repair (replace mdX with the questionable raid device):
 
 
<pre>
 
echo repair > /sys/block/mdX/md/sync_action
 
</pre>
 
 
Depending on the size of the array and disk speed this can take a while.  Watch the progress with:
 
 
<pre>
 
cat /proc/mdstat
 
</pre>
 
 
Once that's done proceed to Step 2.
 
 
=== Step 2 ===
 
 
Issue a check.  It's this check that will reset the mismatch count if there are no problems.  Again replace mdX with your actual raid device.
 
 
<pre>
 
echo check > /sys/block/mdX/md/sync_action
 
</pre>
 
 
Just as before, you can watch the progress with:
 
 
<pre>
 
cat /proc/mdstat
 
</pre>
 
  
 
[[Category:Infrastructure SOPs]]
 
[[Category:Infrastructure SOPs]]

Latest revision as of 18:19, 19 December 2011

Infrastructure InfrastructureTeamN1.png
Shortcut:
ISOP:mismatch_cnt


This SOP has moved to the fedora Infrastructure SOP git repo. Please see the current document at: http://infrastructure.fedoraproject.org/infra/docs/infra-raidmismatch.txt

For changes, questions or comments, please contact anyone in the Fedora Infrastructure team.