Oracle Database 11 g - Online Public Access Catalog

372 CHAPTER 9 ■ STORAGE MANAGEMENT■Note For Oracle Database 11g early adopters, Oracle Clusterware and ASM software and instance can beupgraded independently of the RDBMS. Since optimizer changes between versions cause concerns for largedatabase implementations, you can safely upgrade Clusterware and ASM relatively soon after the generalavailability of Oracle Database 11g. You can leverage this same methodology for future releases of Oracle.Enabling ASM Rolling UpgradesThe rolling upgrade of ASM will provide a higher level of availability for RAC implementations.Similar to the clusterware rolling-upgrade feature introduced in Oracle Database 10g, the OracleASM rolling-upgrade feature will provide higher uptime for RAC environments. To perform arolling upgrade, you must place the ASM instance in rolling-upgrade mode. In addition, youshould make sure all the ASM instances are at the same Oracle version. To enable the ASMinstance for rolling migration mode, you can use this alter system syntax to start rolling migrationto [database_version_number]:SQL> alter system start rolling migration to 11.2.0.2;This command does not actually perform the rolling migration but communicates with allthe ASM instances in the RAC. This command informs the other ASM instance(s) of RAC that itis preparing to perform an upgrade and the states will be temporarily different. Once the rollingmigration is enabled, you can query each ASM instance to view the current state of the ASM:select sys_context ('sys_cluster_properties', 'cluster_state')from dualSQL> /SYS_CONTEXT('SYS_CLUSTER_PROPERTIES','CLUSTER_STATE')-----------------------------------------------------NormalIf the ASM instance were participating in a rolling migration, the output of this querywould indicate a “Rolling Migration” status. Once you confirm the state of the ASM instance isin rolling migration, you can now safely shut down the ASM instance and apply the softwareupgrade to the ASM home. Once you confirm the successful upgrade of the ASM softwarestack, you can now start the ASM instance, which will mount all the diskgroups.Once upgraded, the ASM participates in the RAC in a different version from the other ASMinstances. Only in the rolling migration state are different versions of the ASM instance(s)permissible. It is required that each ASM instance will be put into a rolling migration mode andshut down to prepare for the software upgrade.A Step-by-Step Approach to Rolling UpgradesHere is the step-by-step process to perform a rolling ASM upgrade: