HP AA979A - StorageWorks SAN Switch 2/8V, Administrator'S Manual, Page: 362 / 465

370 Administering Advanced Zoning
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
Description
Single HBA 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.
Application 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.