From Symantec Management Console:
1-Creating connection profile to handle the credentials:
Settings > All Settings, expand the tree Settings > Monitoring and Alerting > Protocol Management > Connection Profiles > Manage Connection Profiles, on the right pane click "Add setting", Specify "Connection profile name", expand "VMWARE",turn the policy on, click the "blue plus" icon, on the new pop-up window choose Credential type: VMWare credentials, Name it, and fill the credentials details. click ok, ok to save your new profile.
2-Adding the ESX Host to VMM:
Home > Virtual Machine Management , drop down "Actions" menu, choose "Add Host", enter the host IP Address then click ok, wait till the discovery task complete on the new pop-up window (need refresh to check status)
3-Assign Connection profile to the discovery task to allow inventory:
Manage > Jobs and Tasks > System Jobs and Tasks > Virtual Machine Management > Network Discovery tasks, you will find the previously ran task, click on it, on the right pane Choose your previously created "Connection profile", then click "Save Changes"
4-Run Inventory Task and schedule it:
Home > Virtual Machine Management, click on your host, right click then choose "Run Inventory", the console will be redirected to the inventory Task, on the right pane click "New Schedule" Set your schedule.
*By default every time you right click the host and run Inventory a new task will be created, this will not prevent the scheduled one from running.
*Best Practice to add several ESX/ESXi hosts is to connect to your "VCENTER" not to add each host by itself as the inventory will run successfully on the latest discovered one only although all the VM's might be populated under the same name of the host.