5.2.3.2 Using Share-Based Resource Management
A share value represents the relative importance of each entity.
With share-based resource allocation, a higher share value implies higher priority and more access to the I/O resources. For example, a database with a share value of 2 gets twice the resource allocation of a database with a share value of 1.
Valid share values are 1 to 32, with 1 being the lowest share, and 32 being the highest share. The sum of all share values in a plan cannot be greater than 32768.
Share-based resource allocation is the recommended method for the
interdatabase plan (dbplan
). For the cluster plan
(clusterplan
), share-based resource allocation is the only
option.
The following example illustrates how to use share-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 a share-based interdatabase plan as follows:
CellCLI> ALTER IORMPLAN -
dbplan=((name=prod, share=16), -
(name=dw, share=4), -
(name=prod_test, share=2), -
(name=DEFAULT, share=1))
By using the example interdatabase plan, the critical OLTP database
(PROD
) gets priority when there is contention for I/O resources.
Specifically, the I/O share for PROD
is 4 times greater than
DW
, 8 times greater than PROD_TEST
, and a 16 times
greater that the default share that is assigned to PROD_DEV
.
At any time, you change the share allocations to adjust the relative priorities.
Parent topic: Administering the IORM Plan