Exchange not updating busy
One of the most confounding problems with Oracle is the resolution of buffer busy wait events.
Buffer busy waits are common in an I/O-bound Oracle system, as evidenced by any system with read (sequential/scattered) waits in the top-five waits in the Oracle STATSPACK report, like this: The main way to reduce buffer busy waits is to reduce the total I/O on the system.
Reducing buffer busy waits reduces the total I/O on the system.
This can be accomplished by tuning the SQL to access rows with fewer block reads by adding indexes, adjusting the database writer or adding freelists to tables and indexes.
I/O contention, resulting in waits for data blocks, is often due to numerous sessions repeatedly reading the same blocks, as when many sessions scan the same index.
In order to look at system-wide wait events, we can query the v$system_event performance view.