On the main dashboard for Spotlight on Oracle RAC there is a Section for Redo Logs, and under it Redo Writes with IO/Sec.
Recently my application performance went way down and the circular arrows were flashing red with high numbers.
However, the number of Redo Log Switches in my Database Alert was normal (3-5 per hour).
So, what does Redo Writes IO/sec on Spotlight really mean?
Per the AWR, Wait Time for Commit (log_file_sync) was very high.
Had a very large shrink table operation in progress at the time, but even when I killed the session, performance did not improve.