Parallel execution processes run on database instances according to service placement
Parallel execution is now aware of the service definition and automatically takes on the appropriate PARALLEL_INSTANCE_GROUPS setting, making it unnecessary to explicitly set the PARALLEL_INSTANCE_GROUPS initialization parameter for an Oracle RAC database. Thus, if you execute a SQL statement in parallel, then the default behavior is for Oracle to run the parallel processes only on the instances that offer the service that you used to connect to the database.
Extending ASM to Nodes Running Single-Instance or Oracle RAC Databases
Using the Database Configuration Assistant (DBCA), you can now add a new ASM instance to a node that is running either a single-instance database or an Oracle RAC database instance.
OCI Runtime Connection Load Balancing
OCI session pools have a new feature called Runtime Connection Load Balancing. OCI session pools are now integrated with the Oracle RAC load balancing advisory to provide load balancing at the time the application gets the connection from the session pool.
Enhanced support for XA transactions in Oracle RAC environments
An XA transaction can now span Oracle RAC instances, allowing any application that uses XA to take full advantage of the Oracle RAC environment. This feature allows the units of work performed across these Oracle RAC instances to share resources and act as a single transaction.
Automatic Database Diagnostics Monitor (ADDM) enhancements for Oracle RAC and Enterprise Manager support
ADDM has been enhanced to provide comprehensive clusterwide performance diagnostic and tuning advice. This enhanced mode of ADDM, called ADDM for Oracle Real Application Clusters, analyzes an Oracle RAC database cluster and reports on issues that are affecting the entire cluster as well as those affecting individual instances.
This feature is particularly helpful in tuning global resources such as I/O and interconnect traffic, making Oracle RAC database management easier and more precise.
In addition, Oracle Enterprise Manager supports ADDM enhancements for Oracle RAC:
• ADDM database-wide analysis for Oracle RAC.
• Targeted ADDM analysis is available for several granularity levels, such as the cluster database, database instance, or for specific targets such as SQL, sessions, services, modules, actions, clients, or wait classes.
ASM preferred mirror read
This feature is useful in extended clusters where remote nodes have asymmetric access with respect to performance. This leads to better storage utilization and lower network loading.ASM in Oracle Database 10g always reads the primary copy of a mirrored extent set. In Oracle Database 11g, when you configure ASM failure groups it might be more efficient for a node to read from a failure group extent that is closest to the node, even if it is a secondary extent. You can do this by configuring preferred read failure groups.
New advanced fault diagnosability infrastructure
The advanced fault diagnosability infrastructure correlates the trace files from across multiple instances. It is collects and manages diagnostic data using the Automatic Diagnostic Repository (ADR) file-based repository, and it uses the ADRCI command-line tool to correlate diagnostics across all instances. Also, you can view the ADR locations by querying the new GV$DIAG_INFO view.
New SYSASM Privilege and OSASM operating system group for ASM Administration
This feature introduces a new SYSASM privilege that is specifically intended for performing ASM administration tasks. Using the SYSASM privilege instead of the SYSDBA privilege provides a clearer division of responsibility between ASM administration and database administration.OSASM is a new operating system group that is used exclusively for ASM. Members of the OSASM group can connect as SYSASM using operating system authentication and have full access to ASM.
ASM supports rolling upgrades
You can perform rolling upgrades of your ASM software on ASM instances in Oracle RAC. This feature enables you to operate with mixed ASM versions starting with Oracle Database 11g release 1 (11.1) and later. As a result, ASM nodes can be independently upgraded or patched without affecting availability of the Oracle RAC database.
ASM manageability features
The new storage administration features for ASM manageability include the following:
• New attributes for disk group compatibility: To enable some of the new ASM features, you can use two new disk group compatibility attributes, COMPATIBLE.RDBMS and COMPATIBLE.ASM. These attributes specify the minimum software version that is required to use disk groups for the database and for ASM respectively. This feature enables heterogeneous environments with disk groups from both Oracle Database 10g and Oracle Database 11g. By default, both attributes are set to 10.1. You must advance these attributes to take advantage of the new features.
New ASM command-line utility (ASMCMD) commands and options: ASCMCMD allows ASM disk identification, disk bad block repair, and backup and restore operations in your ASM environment for faster recovery.
ASM fast rebalance: Rebalance operations that occur while a disk group is in RESTRICTED mode eliminate the lock and unlock extent map messaging between ASM instances in Oracle RAC environments, thus improving overall rebalance throughput.
Convert single-instance ASM instances to cluster ASM Instances with Enterprise Manager and the rconfig utility
You can convert an existing single-instance ASM storage manager to a cluster storage manager, which is required for Oracle RAC databases. You can perform the conversion using either the rconfig command-line utility or Oracle Enterprise Manager Grid Control.
Oracle Enterprise Manager Database Control is enhanced to provide improved ASM manageability
Oracle Enterprise Manager Database Control enables you to more easily manage several ASM tasks, such as managing disk resynchronization, controlling preferred read settings, and managing rolling upgrades.
Optimal Flexible Architecture ensures reliable installations and improves software manageability
This feature improves manageability by making default Oracle Database installations more compliant with Optimal Flexible Architecture (OFA) specifications. As a part of this feature, the Oracle Universal Installer has been updated so that the default installation follows Oracle's Optimal Flexible Architecture. This ensures reliable installations and improves software manageability.
Ability to kill sessions from any instance in a cluster
The new SESSION parameter on the ALTER SYSTEM KILL statement enables you to terminate a session on a specific instance.
Enhanced Oracle Clusterware and Oracle RAC diagnosability, more background processes
This feature provides the ability to run cluster-wide manageability and diagnosability commands to perform health checks, change debugging levels, start and stop the Oracle Clusterware, query the active software version, or show an active nodes list.
DBMS_SCHEDULER package executes and manages jobs in a clustered environment
Oracle Database provides advanced job scheduling capabilities through Oracle Scheduler (the Scheduler). The Scheduler fully supports execution of jobs in a clustered environment. To balance the load on your system and for better performance, you can also specify the database service where you want a job to run.
Enhanced initialization parameter administration
This feature improves database manageability by making it easier to administer the server parameter file (SPFILE). A number of enhancements are being introduced to simplify server parameter file management. Some of these enhancements are:
A more fault tolerant SPFILE
Simplified recovery from the loss of an SPFILE
Redesigned, more intuitive, Enterprise Manager initialization parameter management interface
• Prevention of invalid parameter value settings in SPFILE
• Simplified changing of list parameters
Improved Oracle RAC performance monitoring and diagnostics in Oracle Enterprise Manager
Both Oracle Enterprise Manager Database Control and Oracle Enterprise Manager Grid Control are cluster aware and provide a central console to manage your cluster database. From any location where you can access a web browser, you can manage Oracle RAC databases, Oracle Clusterware, application servers, host computers, and Web applications, as well as related hardware and software.
You now have the ability to see any given metric across database instances or hosts in the cluster as a tile chart. This high-level view capability means that you do not have to access each individual database instance for details if you just want to see inclusive, aggregated information.
You can review issues that are affecting the entire cluster as well as those that are affecting individual instances. This is a major enhancement in terms of how metrics are monitored for Oracle RAC and Oracle Clusterware. With Oracle 11g, you can see the roll-up or summary-based views as well as tile based views if you want to monitor how a metric performs across different instances (hosts) over a period of time.
Also, the Oracle Enterprise Manager Cluster Database Performance page provides a quick glimpse of the performance statistics for a database. Statistics are rolled up across all the instances in the cluster database in charts, and provides a cause and recommended solution for performance problems. There is also information available according to the following sorting methods:
Aggregate by Waits
All activity data is presented in categories: CPU, Scheduler, User I/O, System I/O, Concurrency, Application, Commit, Configuration, Administrative, Network, Cluster and Other. Enterprise Manager rolls up the presented data from all of the running Oracle RAC instances.
Aggregate by Services
Enterprise Manager rolls up all of the activity data for each service. When the activity data is presented in this way, it is simpler to identify which service is most active and thus needs more analysis.
Aggregate by Instances
Enterprise Manager rolls up activity data for each instance.
Database Configuration Assistant (DBCA) no longer manages services
Cluster managed services are no longer managed through DBCA. The best practice for managing services is to use the Cluster Managed Services page in Oracle Enterprise Manager Database Control, which is accessible from the Cluster Database Availability Page.
For more details on RAC and Oracle 11g you can view on ORACLE DBA SUPPORT
OracleDbaSupport.co.uk is a blog site of Sagar Patil, an independent oracle consultant with a great understanding of how the Oracle database engine & Oracle Applications work together.
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