Add RAID fixing

_posts/sysadm/2023-09-15-lvm-cheat-sheet.tl

@@ -21,6 +21,33 @@ List currently used devices and sync status:
 {% endhighlight %}
 
 
+h3. Fix RAID inconsistency due to hardware errors
+
+Run scrubbing - a full scan of RAID LV, which verifies RAID metadata, LV data and
+parity blocks:
+
+{% highlight bash %}
+# lvchange --syncaction check /dev/vgdev/backup
+{% endhighlight %}
+
+If problems are found, this is denoted by @m@ on 9th bit of attributes displayed
+by @lvs@:
+
+{% highlight bash %}
+$ cat /tmp/lvs
+LV      VG    Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync  Convert
+backup  vgdev rwi-aor-m- 4.00g                                     100.00
+{% endhighlight %}
+
+In such case repair ir required. As of LVM tools 2.03.21(2) (2023-04-21)
+@lvchange --syncaction repair@ is unable to deduce which data is correct. The
+only safe choice is to rebuild PV on the failed device:
+
+{% highlight bash %}
+# lvchange --rebuild /dev/sdb1 /dev/vgdev/backup
+{% endhighlight %}
+
+
 h3. Rebuild RAID1 LV with integrity layer
 
 As of LVM tools 2.03.21(2) (2023-04-21) @man lvmraid@ says: