HP A7533A - Brocade 4Gb SAN Switch Base, Administrator'S Manual

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Fabric OS 6.2 administrator guide 235
Zone objects
A zone object is any device in a zone, such as a:
• Physical port number or port index on the switch
• Node World Wide Name (N-WWN)
• Port World Wide Name (P-WWN)
Table 58 Approaches to fabric-based zoning
Zoning
approach
Description
Recommended approach
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 assumes 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.
Alternative approaches
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.
Operating
system
Zoning by operating system has issues similar to zoning by application. In a large site,
this type of zone can become very large and complex. When zone changes are
made, they typically involve applications rather than a particular server type. If
members of different operating system clusters can see storage assigned to another
cluster, they might attempt to own the other cluster’s storage and compromise the
stability of the clusters.
Port allocation Avoid zoning by port allocation unless the administration team has very rigidly
enforced processes for port and device allocation in the fabric.
This type of zoning does, however, provide some positive features. For instance, when
a storage port, server HBA, or tape drive is replaced, the change of WWN for the
new device is of no consequence. As long as the new device is connected to the
original port, it continues to have the same access rights. The ports on the edge
switches can be pre-associated to storage ports, and control of the fan-in ratio (the
ratio of the input port to output port) can be established. With this pre-assigning
technique, the administrative team cannot overload any one storage port by
associating too many servers with it.
Not recommended
No fabric zoning Not using fabric zoning is the least desirable zoning option because it allows devices
to have unrestricted access to the fabric. Additionally, any device attached to the
fabric, intentionally or maliciously, likewise has unrestricted access to the fabric. This
form of zoning should be utilized only in a small and tightly controlled environment,
such as when host-based zoning or LUN masking is deployed.