[Backup/Restore] Fix nits in docs and clarification note.

This fixes some nits in the docs.

This patch adds a note to show that
depending on the MySQL version used
the configuration file can be called
differently.

Change-Id: I1bfcf5566511284cf78422aada29f45b2628bf4b

doc/source/install/controlplane_backup_restore/00_index.rst

@@ -7,7 +7,7 @@ control plane.
 The use case involved in the creation and restore of these procedures are related to the
 possible failures of a minor update or major upgrade for both Undercloud and Overcloud.
 
-The general approach to recovery from failures during the minor update or major upgrade workflow
+The general approach to recover from failures during the minor update or major upgrade workflow
 is to fix the environment and restart services before re-running the last executed step.
 
 There are specific cases in which rolling back to previous steps in the upgrades

doc/source/install/controlplane_backup_restore/01_undercloud_backup.rst

@@ -59,6 +59,13 @@ Filesystem backups
 
 The following command can be used to perform a backup of all data from the undercloud node::
 
-  tar -czf undercloud-backup-`date +%F`.tar.gz /root/undercloud-all-databases.sql /etc/my.cnf.d/server.cnf /var/lib/glance/images /srv/node /home/stack /etc/pki /opt/stack
-
+  tar --ignore-failed-read -czf \
+      undercloud-backup-`date +%F`.tar.gz \
+      /root/undercloud-all-databases.sql \
+      /etc/my.cnf.d \
+      /var/lib/glance/images \
+      /srv/node \
+      /home/stack \
+      /etc/pki \
+      /opt/stack
 

doc/source/install/controlplane_backup_restore/03_undercloud_restore.rst

@@ -17,7 +17,7 @@ Install the MariaDB server with::
 
 Now restore the MariaDB configuration file and database backup, then start the MariaDB server and load the backup in::
 
-  tar -xzC / -f undercloud-backup-$DATE.tar.gz etc/my.cnf.d/server.cnf /root/undercloud-all-databases.sql
+  tar -xzC / -f undercloud-backup-$DATE.tar.gz etc/my.cnf.d/mariadb-server.cnf /root/undercloud-all-databases.sql
   # Edit /etc/my.cnf.d/server.cnf and comment out 'bind-address'
   systemctl start mariadb
   cat /root/undercloud-all-databases.sql | mysql
@@ -25,6 +25,9 @@ Now restore the MariaDB configuration file and database backup, then start the M
   for i in ceilometer glance heat ironic keystone neutron nova;do mysql -e "drop user $i";done
   mysql -e 'flush privileges'
 
+Note that depending on the MySQL version, the config file can
+be `/etc/my.cnf.d/mariadb-server.cnf` or `/etc/my.cnf.d/server.cnf`.
+
 Now create the stack user and restore the stack users home directory::
 
   sudo useradd stack