Article : mismatch_cnt_is_not_0_on_dev_md1

Error message :
WARNING: mismatch_cnt is not 0 on /dev/md1

cat /proc/mdstat
cat /sys/block/md1/md/mismatch_cnt # brings a value other than 0

echo repair >/sys/block/md1/md/sync_action
echo check >/sys/block/md1/md/sync_action

Now the Value should be again 0:
cat /sys/block/md1/md/mismatch_cnt