My Oracle Support Banner

EM 12c: How to Disable Diskmon and ONS Monitor from Enterprise Manager 12c Cloud Control to Stop Notifications: Message=ora.diskmon has 1 instances in OFFLINE State (Doc ID 2060296.1)

Last updated on JANUARY 18, 2023

Applies to:

Enterprise Manager for Oracle Database - Version and later
Information in this document applies to any platform.


EM Cloud Control monitors a RAC database host, on which critical alerts for DiskMon Offline are being generated for the High Availability Service.

Alert content similar to this is in the accompanying notification:

Target type=Oracle High Availability Service
Target name=has_<HOSTNAME>.<DOMAIN>
Message=ora.diskmon has 1 instances in OFFLINE State
Key Value=resource_ora.diskmon.type_ora.diskmon

These errors are harmless for and later database targets. 
The associated metric can be disabled to stop generation of alerts and notifications with the following procedure:


To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.