Smart Flash Log Write-Back
Let us go through what is Smart Flash Log Write-Back in oracle exadata.
On High Capacity Oracle Exadata Storage Servers, all redo log entries must be written to the hard disk drives (HDDs). Even though Exadata Smart Flash Log prevents occasional log write outliers, the total log write throughput is still bound by the HDDs. Consequently, log writes can become a performance bottleneck when I/O bandwidth is saturated on the HDDs, either because of high-volume redo log activity or because of other I/O-intensive activities such as Golden Gate log mining, log archiving, and RMAN backup and restore.
The Smart Flash Log Write-Back feature automatically and transparently stores the entire contents of redo log files using Exadata Smart Flash Cache in Write-Back mode, thereby eliminating the HDDs as a potential performance bottleneck. Depending on the system workload, overall log write throughput can improve up to 250%.
Smart Flash Log Write-Back works transparently in conjunction with Exadata Smart Flash Log. Smart Flash Log Write-Back boosts overall log write throughput, while Exadata Smart Flash Log continues to prevent log write latency outliers.
Smart Flash Log Write-Back works with Oracle Data Guard Primary and Standby databases, boosting throughput for online redo log files and standby redo log files.
If flash cache space resource management is configured in the IORM plan, then caching of redo log files is included in the space accounting for each multitenant container database (CDB) or non-CDB database.
Minimum requirements:
Oracle Exadata System Software release 20.1.0.
Oracle Exadata Database Machine X7.
Exadata Smart Flash Cache in Write-Back mode.
Oracle Database in ARCHIVELOG mode.
