RAC New features in Oracle 9i/10g/11g/12c

Oracle Real Application Clusters New features

Oracle 9i RAC

• OPS (Oracle Parallel Server) was renamed as RAC
• CFS (Cluster File System) was supported
• OCFS (Oracle Cluster File System) for Linux and Windows
• watchdog timer replaced by hangcheck timer

Oracle 10g R1 RAC

• Cluster Manager replaced by CRS
• ASM introduced
• Concept of Services expanded
• ocrcheck introduced
• ocrdump introduced
• AWR was instance specific

Oracle 10g R2 RAC

• CRS was renamed as Clusterware
• asmcmd introduced
• CLUVFY introduced
• OCR and Voting disks can be mirrored
• Can use FAN/FCF with TAF for OCI and ODP.NET
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Oracle 11g R1 RAC

• Oracle 11g RAC parallel upgrades - Oracle 11g have rolling upgrade features whereby RAC database can be upgraded without any downtime.
• Hot patching - Zero downtime patch application.
• Oracle RAC load balancing advisor - Starting from 10g R2 we have RAC load balancing advisor utility. 11g RAC load balancing advisor is only available with clients who use .NET, ODBC, or the Oracle Call Interface (OCI).
• ADDM for RAC - Oracle has incorporated RAC into the automatic database diagnostic monitor, for cross-node advisories. The script addmrpt.sql run give report for single instance, will not report all instances in RAC, this is known as instance ADDM. But using the new package DBMS_ADDM, we can generate report for all instances of RAC, this known as database ADDM.
• Optimized RAC cache fusion protocols - moves on from the general cache fusion protocols in 10g to deal with specific scenarios where the protocols could be further optimized.
• Oracle 11g RAC Grid provisioning - The Oracle grid control provisioning pack allows us to "blow-out" a RAC node without the time-consuming install, using a pre-installed "footprint".

Oracle 11g R2 RAC

• We can store everything on the ASM. We can store OCR & voting files also on the ASM.
• ASMCA
• Single Client Access Name (SCAN) - eliminates the need to change tns entry when nodes are added to or removed from the Cluster. RAC instances register to SCAN listeners as remote listeners. SCAN is fully qualified name. Oracle recommends assigning 3 addresses to SCAN, which create three SCAN listeners.
• Clusterware components: crfmond, crflogd, GIPCD.
• AWR is consolidated for the database.
• 11g Release 2 Real Application Cluster (RAC) has server pooling technologies so it’s easier to provision and manage database grids. This update is geared toward dynamically adjusting servers as corporations manage the ebb and flow between data requirements for datawarehousing and applications.
• By default, LOAD_BALANCE is ON.
• GSD (Global Service Deamon), gsdctl introduced.
• GPnP profile.
• Cluster information in an XML profile.
• Oracle RAC OneNode is a new option that makes it easier to consolidate databases that aren’t mission critical, but need redundancy.
• raconeinit - to convert database to RacOneNode.
• raconefix - to fix RacOneNode database in case of failure.
• racone2rac - to convert RacOneNode back to RAC.
• Oracle Restart - the feature of Oracle Grid Infrastructure's High Availability Services (HAS) to manage associated listeners, ASM instances and Oracle instances.
• Oracle Omotion - Oracle 11g release2 RAC introduces new feature called Oracle Omotion, an online migration utility. This Omotion utility will relocate the instance from one node to another, whenever instance failure happens.
• Omotion utility uses Database Area Network (DAN) to move Oracle instances. Database Area Network (DAN) technology helps seamless database relocation without losing transactions.
• Cluster Time Synchronization Service (CTSS) is a new feature in Oracle 11g R2 RAC, which is used to synchronize time across the nodes of the cluster. CTSS will be replacement of NTP protocol.
• Grid Naming Service (GNS) is a new service introduced in Oracle RAC 11g R2. With GNS, Oracle Clusterware (CRS) can manage Dynamic Host Configuration Protocol (DHCP) and DNS services for the dynamic node registration and configuration.
• Cluster interconnect: Used for data blocks, locks, messages, and SCN numbers.
• Oracle Local Registry (OLR) - From Oracle 11gR2 "Oracle Local Registry (OLR)" something new as part of Oracle Clusterware. OLR is node’s local repository, similar to OCR (but local) and is managed by OHASD. It pertains data of local node only and is not shared among other nodes.
• Multicasting is introduced in 11gR2 for private interconnect traffic.
• I/O fencing prevents updates by failed instances, and detecting failure and preventing split brain in cluster. When a cluster node fails, the failed node needs to be fenced off from all the shared disk devices or diskgroups. This methodology is called I/O Fencing, sometimes called Disk Fencing or failure fencing.
• Re-bootless node fencing (restart)‏ - instead of fast re-booting the node, a graceful shutdown of the stack is attempted.
• Clusterware log directories: acfs*
• HAIP (IC VIP).
• Redundant interconnects: NIC bonding, HAIP.
• RAC background processes: DBRM – Database Resource Manager, PING – Response time agent.
• Virtual Oracle 11g RAC cluster - Oracle 11g RAC supports virtualization.

Here are the new features in Oracle 12c RAC/Clusterware.

1. Oracle Flex ASM - This feature of Oracle Clusterware 12c claims to reduce per-node overhead of using ASM instance. Now the instances can use remote node ASM for any planned/unplanned downtime. ASM metadata requests can be converted by non-local instance of ASM.

2. ASM Disk Scrubbing - From RAC 12c, ASM comes with disk scrubbing feature so that logical corruptions can be discovered. Also Oracle 12c ASM can automatically correct this in normal or high redundancy diskgroups.

3. Oracle ASM Disk Resync & Rebalance enhancements.

4. Application Continuity (AC) - is transparent to the application and in-case the database or the infrastructure is unavailable, this new features which work on JDBC drivers, masks recoverable outages. This recovers database session beneath the application so that the outage actually appears to be delayed connectivity or execution. Transaction guard (improvements of Fast Application Notification).

5. IPv6 Support - Oracle RAC 12c now supports IPv6 for Client connectivity, Interconnect is still on IPv4.

6. Per Subnet multiple SCAN - RAC 12c, per-Subnet multiple SCAN can be configured per cluster.

7. Each RAC instance opens the Container Database (CDB) as a whole so that versions would be same for CDB as well as for all of the Pluggable Databases (PDBs). PDBs are also fully compatible with RAC.

8. Oracle installer will run root.sh script across nodes. We don't have to run the scripts manually on all RAC nodes. 

9. new "ghctl" command for patching.

10. TAF is extended to DML transactions failover (insert/update/delete).

Source: Internet