Exadata Storage Server High Availability

Ensuring the high availability of the database storage grid is important for enhancing the overall availability of the Database Machine. Oracle ASM provides built-in high-availability features by incorporating Grid RAID, as outlined in Chapter 5. With Grid RAID, when an underlying disk on the Exadata Storage Server fails, the data is still available from the mirrored copy placed on a different Exadata Storage Server. ASM also incorporates built-in protection from data corruption, through which it will transparently access a mirrored copy when the primary copy is found to be corrupt.

Although the ASM redundancy level of NORMAL provides protection from multiple, simultaneous, failures and corruptions occurring in a single Exadata Storage Server, it may not protect you when the failures are spread across multiple Exadata Storage Servers. In such situations, your option for recovery is to perform a restore from a backup or to fail over to the Data Guard standby database (if it is configured).