This switch enables databases to be transparently relocated onto new servers without the need to modify applications connections to the database.The database servers, in turn, are connected to a shared storage such as SAN, such that database files can be quickly remapped onto a different server.Corporations have invested millions of dollars in computing hardware.
A new server is purchased, and the database is moved to the new server.
Then the old server becomes available, and another database is migrated onto the old server.
Figure 1 illustrates how easily computing resources can be added at the Web server and application server levels.
Large enterprises can add and remove application servers on a just-in-time basis, always ensuring that there are appropriate computing resources to match the load of their end-user community.
It is important to note that the DAN technology is a Decision Support System (DSS) because it provides the Oracle DBA with both visibility into database resource usage (including current and historical charts) as well as recommendations for changes, deferring to the DBA for the final resolution.
The management console allows servers and databases to be easily added to and removed from the DAN.
This article explores a new approach to Oracle technology that "virtualizes" the database layer, allowing for transparent relocation of Oracle database instances onto the most available servers, and enabling optimal utilization and just-in-time expansion of server resources.
To fully comprehend the solution, you must first understand the problem.3) Time Consuming: In many large Oracle shops, a "shuffle" occurs when a database outgrows its server.
The internal mechanism for relocation may be quite complex, but the idea is simple. In a SAN environment, relocation of a database instance involves the following steps: A typical time for such relocation is 10 20 seconds.
Using products such as Oracle's Transparent Application Failover (TAF) may allow instance relocation to be performed such that the move to another server is transparent to the database clients and application end users.
With the exception of complex parallel architectures such as Oracle's Real Application Clusters, database management systems can generally run on only one server at a time, and databases must be moved between servers manually.