Tuesday, July 25, 2006

OPS and RAC part 1

URLs: OPS
Link 1

Link 2 : Comparing RAC and OPS

Link 3 : OPS installation (from HP )

Link 4: Quest Mag

Oracle 7/8/8i OPS and 9i RAC

OPS: 1 data base ::multiple instances access the database.
A normal Oracle installation consists of a single Oracle instance that accesses a database on the same computer system. With the parallel server option (PSO), multiple instances on different computer systems (nodes) can access the same database files simultaneously.
With Oracle Parallel Server installations, multiple instances mount the same database files. Communication between instances is managed by the Distributed Lock Manager (DLM). Note that the DLM is hardware and operating system dependent.




What are the benefits of the Oracle Real Application Clusters and Oracle Parallel Server Primary/Secondary configuration?

The primary/secondary configuration masters locks at the primary instance. This has a number of advantages:

  • at the primary instance, the communication with the DLM is fast as there is no latency across the interconnect, giving performance similar to single instance Oracle.
  • the time to reconfigure the locks is faster as they are located locally, allowing use a larger number of releaseable hash locks than was recommended for primary/secondary pre-8.1.6 configurations. This allows the secondary instance to be used for secondary tasks including warming the cache.
  • With local mastering there is minimal cost when the secondary instance leaves and rejoins the cluster.

In addition, Primary/Secondary configuration enforces primary/secondary access through the use of roles. This prevents unintended connections to the secondary instance.
[ source...]

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