The exadata development team has now released the exadata cell software version 11.2.2.4.0, which includes a new feature called the “Smart Flash Log”.

In a nutshell, this new feature speeds up redo log writes. Exadata smart flash log uses Exadata smart flash cache as a temporary storage to provide low latency redo log writes. With this new feature enabled, oracle writes both to physical disk and the flash cache simultaneously.

So if for some reason, flash cache writes are slow, the writes to the physical disk will provide the good response times. Similarly if the physical disk writes are slow, the flash cache writes will complete faster, providing the good response times.

You can use the “Create flash log”, cell command to turn this feature on. You can use the “Drop flash log” cell command to turn this feature off.

The exadata storage server software, users guide, has been updated with this information.

You have to have Bundle patch 11 (Actually it works from BP9 onwards, but BP11 is recommended) and exadata cell software 11.2.2.4.0 applied to get this functionality.

Please read the section “Exadata Smart Flash Logging : Flash for database logging”, in the oracle technical white paper, Exadata smart flash cache features and the Oracle Exadata Database Machine, for details.

Here is a video tutorial produced by Oracle Education on this topic, smart flash log.