Question: I work in an Oracle shop, but I do
not have much experience with the higher level functionality like
RAC and Grid computing. Are they the same thing?
If not, what is the difference between RAC and Grid computing?
Answer: To start with, Oracle Real
Application Clusters (RAC) are a database system involving a
configuration of multiple hosts or servers joined together with
clustering software and accessing the shared disk storage
structures. On each of the hosts in the cluster, an Oracle Database
instance is launched that uses the shared storage structures to
provide the logical database objects. Thus, the multiple database
instances provide a common database access for the users. Users can
access the same database from any of the instances. RAC is a
high availability solution, but care should be taken when
deciding to implement RAC.
Oracle's original Grid vision represented a pool of database
servers, storage and networks in an inter-related resource platform.
Effective Management of workload within the grid database computing
arena was a key feature. RAC Database and clustering technology
helped to set up and manage the overall Oracle Grid strategy. Still
today, database processing and capability can be easily and
dynamically added with the RAC technology.
Thus, RAC is an integral part of Grid computing, but it is not the sum
total of it. The goal of Grid computing is to supply high
availability information sharing supported by an architecture with
sufficient resource allocation such that users can rely on getting
as much information or processing as they need on demand.
Users no longer have to consider where their data is being stored or
where their data request are processed because the database grid is
supported by RAC and Oracle Clusterware and the storage grid is
supported by the Automatic Storage Management (ASM) system.
For those not yet comfortable with working without a net on
diagnostics and tuning of their system, Oracle Enterprise Manager
(OEM) can be purchased to aid in the holistic oversight of the
Read more about the
difference between Oracle RAC and Grid.
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