2.1 Capacity-On-Demand

You can reduce the number of active cores on your Exadata database servers to lower the initial software licensing cost, but this does not change the hardware cost.

Capacity-on-demand (CoD) refers to an Exadata database server that is installed with a subset of its cores disabled so that the database software license cost can be reduced. During initial system configuration, you can set the number of active cores (within applicable limits) using Oracle Exadata Deployment Assistant (OEDA). The number of active cores can be increased at a later time, when more capacity is needed. However, after initial installation, the total active core count may only be increased, but not decreased. Capacity-on-demand does not apply to Oracle Exadata storage server cores.

After initial installation active cores may only be deactivated when you are adding database servers to an Exadata configuration and redistributing the active cores in order to maintain a balanced cluster configuration. In that case, the total number of active cores across all database servers cannot decrease and the end state must comply with the capacity-on-demand restrictions. For example, consider an Exadata X10M system with 96 active cores on two database servers. If you want to add a third database server and increase the total core count to 120 cores, then you can reduce the number of active cores from 48 to 40 on each of the first two database servers, and install the new database server with 40 active cores.

Note:

Oracle recommends that all database servers in a cluster have the same number of active cores.

When you use capacity-on-demand in conjunction with virtual machines (VMs), the VM server (OVM Management Domain [Dom0] or KVM Host) reserves one core on each physical CPU. For example, on an Exadata X10M database server with two physical CPUs and a total of 192 CPU cores, a maximum of 190 cores can be used by the VMs. The CPU cores reserved for the VM server do not require Oracle Database licenses.

It is your responsibility to acquire the required software licenses. For steps on how to increase the number of active cores, refer to Oracle Exadata Database Machine Maintenance Guide.

Tip:

When you run Oracle Exadata Deployment Assistant (OEDA) to perform initial configuration of your Exadata system, you must specify whether or not you are using capacity-on-demand, and if so, the number of cores that you want to activate on your system. Because it is not possible to decrease the total number of active cores after installation, it is recommended that you review your licensing plan to ensure that you specify the correct number of active cores that you intend to license and use.

• Restrictions for Capacity-On-Demand on Oracle Exadata Database Machine
  Capacity-on-demand is available for Exadata Database Machine, starting with X4-2 systems.
• Monitoring Tool Requirement
  To use the capacity-on-demand feature, the Exadata system must be running an approved monitoring tool so that the number of active cores can be validated.

2.1.1 Restrictions for Capacity-On-Demand on Oracle Exadata Database Machine

Capacity-on-demand is available for Exadata Database Machine, starting with X4-2 systems.

Note the following restrictions regarding capacity-on-demand:

• For X5-2, X6-2, X7-2, X8-2, X8M-2, X9M-2, and X10M systems, the minimum number of cores that must be enabled is 14 per database server. Note that for Eighth Rack configurations the minimum is 8 cores per database server.
• For X5-8, X6-8, X7-8, X8-8, X8M-8, and X9M-8 systems, the minimum number of cores that must be enabled is 56 per database server.
• For X4-2 systems, the minimum number of cores that must be enabled is 12 per database server. The X4-2 Eighth Rack configuration cannot use capacity-on-demand.
• For X4-8 systems, the minimum number of cores that must be enabled is 48 per database server.
• Additional cores are increased in 2-core increments per database server on X4-2 and later two-socket systems, and in 8-core increments on X4-8 and later eight-socket systems.
• Within the same Exadata system, each database server can be licensed to a different number of cores, but each server in the same cluster should have the same number of active cores to accommodate a cluster fail over without significant performance impact.
• CPU oversubscription for KVM guests is not permitted when capacity-on-demand is used on Exadata X10M KVM hosts. CPU oversubscription is only allowed on Exadata X10M when all CPU cores are active on the KVM hosts.

2.1.2 Monitoring Tool Requirement

To use the capacity-on-demand feature, the Exadata system must be running an approved monitoring tool so that the number of active cores can be validated.

The monitoring tool must be installed within three months of installation. To meet this requirement, you can do any of the following:

• Purchase the Oracle technical support services necessary to enable eligibility for Oracle Platinum Services, and then continuously maintain those services.

• Install, and then continuously utilize Oracle Enterprise Manager.

  The base installation collects appropriate information from the server system, including the number of active cores. No add-on packs need to be purchased. The rules for using Oracle Enterprise Manager are the same as those that apply to Oracle Trusted Partitions.