Replaced once the junk drive in the software RAID1, added it to the raid, it successfully synchronized, installed GRUB.
After a while I received an email message:
Subject: Cron <root@server> /usr/sbin/raid-check WARNING: mismatch_cnt is not 0 on /dev/md2
In my case, raid-check found that the mismatch_cnt counter is not equal to 0 for /dev/md2, which means that there may be broken sectors on the disk, or it simply needs to be resynchronized. Since I installed GRUB after adding the disk to the raid, this is probably the cause.
Example of viewing the counters of all arrays:
Or each in turn:
cat /sys/block/md0/md/mismatch_cnt cat /sys/block/md1/md/mismatch_cnt cat /sys/block/md2/md/mismatch_cnt
View the status of raids:
If mismatch_cnt is not 0 for any array, then you can try to resynchronize it:
echo 'repair' >/sys/block/md2/md/sync_action
echo 'check' >/sys/block/md2/md/sync_action
If you want to cancel the action:
echo 'idle' >/sys/block/md2/md/sync_action
Let’s see the synchronization status and other data of the array: