10.1.2 Exadata I/O Latency Capping

Disks drives or flash devices can, on rare occasion, exhibit high latencies for a small amount of time while an internal recovery operation is running. In addition, drives that are close to failing can sometimes exhibit high latencies before they fail. This feature masks these very rare latency spikes by redirecting read I/O operations to a mirror copy.

Oracle Exadata Storage Server Software automatically redirects read I/O operations to another cell when the latency of the read I/O is much longer than expected. This is performed by returning a message to the database that initiated the read I/O. The database then redirects the I/O to another mirror copy of the data. Any I/Os issued to the last valid mirror copy of the data is not redirected.

Minimum software: Oracle Database 11g Release 2 (11.2) release Monthly Database Patch For Exadata (June 2014 - 11.2.0.4.8). The same release is required for Grid Infrastructure.