Features in Oracle 9i/10g/11g RAC

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

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.
• ADR command-line tool - Oracle Automatic Diagnostic repository (ADR) has a new command-line interface named ADRCI, ADR Command Interface. ADRCI can be used to access the 11g alert log:
  $adrci
  adrci> show alert
• 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".
• Data Guard - Standby snapshot - The new standby snapshot feature allows us to encapsulate a snapshot for regression testing. We can collect a standby snapshot and move it into our QA database, ensuring that our regression test uses real production data.
• Quick Fault Resolution - Automatic capture of diagnostics (dumps) for a fault.

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.
  
• 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.
• 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.
• 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.
• racone2rac - to convert RacOneNode back to RAC.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.
  
  Source: http://satya-racdba.blogspot.in