Are your Oracle archived log files much too small?


 

Have you ever noticed that your archived redo logs can be much smaller than the online redo logs and may display a wild variation in size? This difference is most likely to happen in systems with a very large SGA (system global area), and the underlying mechanisms may result in Oracle writing data blocks to disc far more aggressively than is necessary. This article is a high-level description of how Oracle uses its online redo logs and why it can end up generating archived redo logs that are much smaller than you might expect.

Background

I’ll start with some details