10.3.6 Health Factor for Predictive Failed Disk Drop

When a hard disk enters predictive failure on Oracle Exadata Storage Server, Oracle Exadata System Software automatically triggers an Oracle Automatic Storage Management (Oracle ASM) rebalance to relocate data from the disk. The Oracle ASM rebalance first reads from healthy mirrors to restore redundancy. If all other mirrors are not available, then Oracle ASM rebalance reads the data from the predictively-failed disk. This diverts rebalance reads away from the predictively-failed disk when possible to ensure optimal rebalance progress while maintaining maximum data redundancy during the rebalance process.

Before the data is completely relocated to other healthy disks in the disk group, Oracle Exadata System Software notifies database instances of the poor health of the predictively-failed disk so that queries and smart scans for data on that disk will be diverted to other mirrors for better response time.