Q-Logic SN0054651-00 F manual RAID Configuration and LUN Masking, Adapters, System

A

System Overview Configurations

RAID Configuration and LUN Masking

Figure 2-4illustrates the interaction of an adapter alternate with a LUN alternate in a RAID subsystem. Two hosts (X and Y) connect to a fabric, which is simplified for this diagram. Also on the fabric is a RAID subsystem with dual controllers (left and right) containing eight LUNs.

Host X

LUNs 0–3

A

Adapters

B

	Left
Fabric		RAID
		System

Right

A

LUNs 0–7

Host Y

LUNs 4–7

Controllers

Adapters

B

Figure 2-4 RAID Configuration and LUN Masking

Figure 2-4is a generic example of a RAID configuration. Many, but not all, RAID systems operate in this manner. The following paragraphs describe this configuration:

„All hosts and storage devices are connected to a common fabric. Details of fabric configuration are not important, except to note that all hosts and adapters can connect to all storage devices. Depending on the fabric, some devices may appear on the local loop and as fabric devices.

„Hosts X and Y must be configured to recognize different target devices or else risk overwriting each other's data. SANsurfer FC HBA Manager must be run on each host to configure devices as enabled (with a preferred and alternate path assigned to each device) or disabled.

„If hosts X and Y are cooperating in a cluster, they can be configured so that both recognize a specific device. In this case, clustering software and the clustered application must determine which host is permitted to write to the device.

SN0054651-00 F 2-5