9.9. Summary

In this chapter, we showed you how Automatic Storage Management (ASM) can reduce or eliminate the headaches involved in managing the disk space for all Oracle file types, including online and archived logs, RMAN backup sets, flashback logs, and even initialization parameter files (SPFILEs).

We reviewed the concepts related to a special type of instance called an ASM instance along with the initialization parameters specific to an ASM instance. In addition, we described the dynamic performance views that allow you to view the components of an ASM disk group as well as to monitor the online rebalancing operations that occur when disks are added or removed from a disk group. Starting and stopping an ASM instance is similar to a traditional database instance, with the added dependencies of database instances that use the disk groups managed by an ASM instance and therefore will not be available to users if the ASM instance is not available to service disk group requests.

ASM filenames have a number of different formats and are used differently depending on whether existing ASM files or new ASM files are being referenced. ASM templates are used in conjunction with ASM filenames to ease the administration of ASM files.

Near the end of this chapter, we reviewed ASM disk group architecture, showing how failure groups can provide redundancy and performance benefits while at the same time eliminating the need for a third-party logical volume manager. Dynamic disk group rebalancing automatically tunes I/O performance when a disk is added or deleted from a disk group or a disk in a disk group fails. While we focused on the SQL commands necessary to manage disk groups, we also presented the EM Database Control interface for performing these same operations.