Defining QoS Properties

In addition to the Storage Class and the priority level for a logical volume, you must also define two other Quality of Service (QoS) properties for the volume: the RAID level and the read-ahead policy. The Oracle FS System provides two approaches to defining the RAID level and the read-ahead policy.

Note: When you create a LUN, the system automatically sets the RAID level and the read-ahead policy. You can override those default properties from the Create SAN LUN dialog by selecting Custom in the Storage Profile field.

You can customize the settings for the RAID level and for the read-ahead policy by using one of the following approaches:

Basic approach: Using the basic approach, you indirectly specify the RAID level and the read-ahead policy for the volume. Using this approach, you specify the data redundancy, the I/⁠O bias, and the access bias of a logical volume. These QoS properties are referred to as the basic QoS properties of the volume.
Advanced approach: Using the advanced approach, you directly specify the RAID level and the read-ahead policy for a logical volume. These QoS properties are referred to as the advanced QoS properties of the volume.

Note: In Oracle FS System Manager (GUI), when customizing the QoS properties of a logical volume, you can set the basic QoS properties of the volume and then map them to the advanced QoS properties. You cannot, however, set the advanced QoS properties and then map them to the basic QoS properties.

The following table summarizes how the basic QoS properties map to the advanced QoS properties of a volume.

Table 1 Mapping QoS properties
Initial Storage Class	Initial redundancy	Basic QoS properties		Advanced QoS properties
Initial Storage Class	Initial redundancy	Initial typical access	Initial I/O bias	Initial RAID level	Initial read-ahead
Capacity disk	Double	Sequential	Read	RAID 6	Aggressive
Capacity disk	Double	All others	All others	RAID 6	Normal
All other Storage Classes	Single	Sequential	Read	RAID 5	Aggressive
		Random	Write	RAID 10 (mirrored)	Normal
		All others	All others	RAID 5	Normal