QoS Plus Controls

The QoS Plus feature consumes resources that might affect overall system performance. You can control certain aspects of this feature to mitigate some of those effects.

The Oracle FS System monitors the I/⁠O activity to determine the best time to migrate the data to another storage tier. When the system activity is low, tier migration efforts increase. Conversely, when the system load is heavy, tier migration efforts decrease, but do not cease.

Scanning

Oracle FS System Manager (GUI) provides various options that together optimize your storage utilization costs and the overall performance of the I/⁠O operations. The options affect when QoS Plus scans your data and when QoS Plus moves the data among the available Storage Classes.

To match your application activity, you can provide delays to the scan frequency that is used by QoS Plus.

Tier Reallocation

You can disable the data migration feature at both the Storage Domain and LUN levels. Disabling data migration at the Storage Domain prevents data migration for all LUNs that are assigned to that Storage Domain. You can prevent data migration for a single LUN by deselecting the Tier Reallocation option in the Additional Options dialog. The options for disabling data migration at the Storage Domain and LUN levels are independent. For example, if you make a data migration change to the Storage Domain, that change does not affect the settings for the LUN.

Capacity Limits

By default, QoS Plus uses all of the available storage capacity in a Storage Domain. For each Storage Class in a given Storage Domain, you can specify the percentage of storage capacity that the Oracle FS System can use for QoS Plus LUNs. Specifying a percentage of the capacity that can be used for QoS Plus is most useful for the Storage Classes that are relatively expensive.

You can allocate, for example, 80% of your performance HDD capacity for auto‑tiered LUNs, which then leaves 20% of that capacity for LUNs using regular QoS.

Note: Reducing the amount of QoS Plus storage capacity below the amount of capacity that is currently being used causes the system to migrate data to available Storage Classes only if the storage capacity is available. You might need to free some storage capacity before the system can use the desired allocated percentage of your storage capacity.