With allocation-based resource management, each allocation is associated with a level. Valid level values are from 1 to 8, and the sum of allocation values cannot exceed 100 for each level. Resources are allocated to level 1 first, and then remaining resources are allocated to level 2, and so on.

Though not recommended, allocation-based resource management can be used in the interdatabase plan (dbplan). For the category plan (catplan), allocation-based resource management is the only option.

The following example illustrates how to use allocation-based resource management in an interdatabase plan. Consider four databases sharing the same Oracle Exadata Storage Server resources. The four databases are:

• A critical OLTP production database, named PROD
• A test database, named PROD_TEST
• A development database, named PROD_DEV
• A data warehouse database, named DW

An OLTP production database typically issues small I/O requests, and low latency for these requests is the critical requirement. A data warehouse issues large numbers of large I/O requests and is more sensitive to the I/O throughput than the latency of each individual I/O request. Without any I/O resource management, the large number of I/O requests issued by the DW database could overwhelm the storage subsystem and increase the latency of the I/O requests issued by the PROD database. Additionally, the I/O requests issued by the test and development databases, PROD_TEST and PROD_DEV, could adversely affect the performance of the PROD and the DW databases.

To ensure a reasonable distribution of I/O resources, you can define an allocation-based interdatabase plan as follows:

CellCLI> ALTER IORMPLAN                                       -
         dbPlan=((name=prod, level=1,allocation=80),          -
                 (name=dw, level=2, allocation=80),           -
                 (name=prod_test,  level=3, allocation=50),   -
                 (name=prod_dev, level=3, allocation=40),     -
                 (name=OTHER, level=3, allocation=10))

By using the example interdatabase plan:

• The critical OLTP database (PROD) is guaranteed 80 percent of the I/O resources during periods of I/O resource contention.
• The DW database gets 80 percent any remaining unused I/O.
• Finally, the PROD_TEST and PROD_DEV databases get any unused I/O in the amount of 50 percent and 40 percent respectively. Also, in this example, a 10% allocation is reserved for OTHER databases that are not explicitly listed in the plan.

At any time, you change the allocations to adjust the resource assignments.