I’ve seen some posts on the blogosphere where people attempt to explain (or should I say guess) how Exadata Smart Flash Logging works and most of them are wrong. Hopefully this post will help clear up some the misconceptions out there.
The following is an excerpt from the paper entitled “Exadata Smart Flash Cache Features and the Oracle Exadata Database Machine” that goes into technical detail on the Exadata Smart Flash Logging feature.
Smart Flash Logging works as follows. When receiving a redo log write request, Exadata will do
parallel writes to the on-disk redo logs as well as a small amount of space reserved in the flash
hardware. When either of these writes has successfully completed the database will be
immediately notified of completion. If the disk drives hosting the logs experience slow response
times, then the Exadata Smart Flash Cache will provide a faster log write…
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