This is where the flow of the Spotlight on Oracle Data Guard home page starts. The Redo Log Writer writes Redo Buffer Blocks to the Redo Logs.
The Redo Log Writer also writes to the Log Network Server. If the Transport Method is Synchronous (or Parallelsync) then a bottleneck at the Network or Standby could prevent the Log Network Server from flushing. The Redo Log Writer would write the overflow through to the Redo Logs to be transferred to the Standby via the Archiver.
Note: A number of alarms are associated with LGWR on Spotlight on Oracle. Those alarms are raised when applicable on the Spotlight on Oracle home page. They are not raised on the Spotlight on Oracle Data Guard home page.