add backup/restore information

README.md

@@ -88,6 +88,25 @@ kubectl exec -n opennebula -i -c oned <each_oned_pod> -- sh -c 'zcat | mysql -h$
 then disable debug
 
 
+## Upgrade notes
+
+```
+kubectl get pod -n opennebula -l role=leader
+```
+
+Perform backup:
+```
+kubectl exec -n opennebula -c oned <leader_pod> -- sh -c 'mysqldump -h$DB_SERVER -u$DB_USER -p$DB_PASSWD $DB_NAME | gzip -9' > opennebula-db.sql.gz
+```
+
+**To restore**, redeploy release with `--set oned.debug=true` and:
+```
+kubectl exec -n opennebula -i -c oned <each_oned_pod> -- sh -c 'zcat | mysql -h$DB_SERVER -u$DB_USER -p$DB_PASSWD -D$DB_NAME' < opennebula-db.sql.gz
+```
+
+then disable debug
+
+
 ## Upgrade notes
 
 The minor upgrades can be performed by standard way using rolling update, however major updates must be performed by fully chart reinstallation.