HP StorageWorks 2/16V HP StorageWorks Fabric OS 5.3.x administrator guide (569 - Page 362

Zone types Table 88 summarizes the types of Zoning. Table 88 Types of Zoning Zone type Description Storage-based Storage units typically implement LUN-based Zoning, also called LUN masking. LUN-based Zoning limits access to the LUNs on the storage port to the specific WWN of the server HBA. It is needed in most SANs. It functions during the probe portion of SCSI initialization. The server probes the storage port for a list of available LUNs and their properties. The storage system compares the WWN of the requesting HBA to the defined zone list, and returns the LUNs assigned to the WWN. Other LUNs on the storage port are not made available to the server. Host-based Host-based Zoning can implement WWN or LUN masking. Fabric-based Fabric switches implement fabric-based Zoning, in which the zone members are identified by WWN or port location in the fabric. Fabric-based Zoning is also called name server-based or soft Zoning. When a device queries the fabric name server, the name server determines the zones in which the device belongs. The server returns information on all members of the zones in the fabric to the device. Devices in the zone are identified by node WWN, port WWN, or (domain, port) of the switch to which the device is connected. The primary approaches to fabric-based Zoning are summarized in Table 89. Table 89 Approaches to fabric-based Zoning Zoning approach Single HBA Application Description Zoning by single HBA most closely re-creates the original SCSI bus. Each zone created has only one HBA (initiator) in the zone; each of the target devices is added to the zone. Typically, a zone is created for the HBA and the disk storage ports are added. If the HBA also accesses tape devices, a second zone is created with the HBA and associated tape devices in it. In the case of clustered systems, it could be appropriate to have an HBA from each of the cluster members included in the zone; this is equivalent to having a shared SCSI bus between the cluster members and presumes that the clustering software can manage access to the shared devices. In a large fabric, Zoning by single HBA requires the creation of possibly hundreds of zones; however, each zone contains only a few members. Zone changes affect the smallest possible number of devices, minimizing the impact of an incorrect zone change. This Zoning philosophy is the preferred method. Zoning by application typically requires Zoning multiple, perhaps incompatible, operating systems into the same zones. This method of Zoning creates the possibility that a minor server in the application suite could disrupt a major server (such as a Web server disrupting a data warehouse server). Zoning by application can also result in a zone with a large number of members, meaning that more notifications, such as registered state change notifications (RSCNs), or errors, go out to a larger group than necessary. 370 Administering Advanced Zoning