storage-connector docs - manual restart of iscsi services

Manual Restart of iSCSI Services

If the config value for enable-auto-restarts option is set to True, iSCSI changes (e.g.: to the initiator-dictionary) trigger restarts on all nodes where storage-connector is deployed. This behaviour might not be acceptable since restarting the iSCSI service may cause volumes in use to be unmounted.

As a consequence, enable-auto-restarts defaults to False, which allows operators to manually roll out changes on a unit-by-unit basis. When ready to apply pending changes, the user is can run an action to manually restart the iSCSI service on the unit as shown below

juju run storage-connector/0 restart-services --params services="iscsid open-iscsi"

On the other hand, the iscsi-discovery-and-login config defaults to True, which will cause the charm to run the iscsiadm discovery and login against the iSCSI target after charm-managed iSCSI services restart (triggered by either config changes or by the restart-services action).

If desired, discovery and login can also be controlled manually on a per-app basis by setting the config option to False and running the iscsi-discovery-and-login action.