Update disaster_recovery.rst (#556)

Added mandatory step for disaster recovery from Cockpit.

Co-authored-by: Giacomo Sanchietti <giacomo.sanchietti@nethesis.it>

administrator-manual/en/disaster_recovery.rst

@@ -59,15 +59,18 @@ Please, follow below steps:
 5. Map network interface names from the backup to the running system.
    This step is required only if :guilabel:`Restore network configuration` option is enabled.
 
-6. Click the :guilabel:`Restore` to start the restore process.
+6. During disaster recovery, to obtain a machine identical to original one, it's **mandatory** to keep the option :guilabel:`Reinstall packages` **enabled**!
+   Its deactivation could introduce unexpected behavior on restored system!
+
+7. Click the :guilabel:`Restore` to start the restore process.
 
    .. note::
 
       If you're connected to a network interface that will change the IP address during the restore,
       you will be disconnected from the Server Manager and you will need to login again using the
       new IP address.
 
-7. Verify the system is functional and then access the :guilabel:`Backup` page.
+8. Verify the system is functional and then access the :guilabel:`Backup` page.
    To restore all files, click on :guilabel:`Restore` button under the **Data Backup** section,
    select the name of the backup and click the :guilabel:`Restore` button.