Unable to get SQL Server Agent to start when using a domain account. Recently this was observed when attempting to move the cluster group from one SQL node to the other. Failover was unsuccessful because the SQL Server Agent would not start on the second node. The following error was in the event log.
Event Type: Error Event Source: SQLSERVERAGENT Event Category: Service Control Event ID: 103 Date: 3/28/2007 User: N/A Computer: SQL2 Description: SQLServerAgent could not be started (reason: SQLServerAgent must be able to connect to the SQL Server as SysAdmin, but '(Unknown)' is not a member of the SysAdmin role).
There are multiple reasons for this, but one step is to modify the Local Security Settings in Administrative Tools on the node where the agent will not start
Administrative Tools -> Local Security Policy -> >Local Policies -> User Rights Assignment - > Lock pages in memory Properties.
Add the Domain\AD account to the ‘Lock Pages in Memory’, reboot the server and attempt the failover again