SAN fabric overview

The SAN fabric is an area of the network that contains routers and switches. A SAN is configured into a number of zones. A device using the SAN can communicate only with devices that are included in the same zones that it is in. A SAN Volume Controller cluster requires several distinct types of zones: a cluster zone, host zones, and disk zones. The intercluster zone is optional.

In the host zone, the host systems can identify and address the SAN Volume Controller nodes. You can have more than one host zone and more than one disk zone. The cluster zone contains all ports from all SAN Volume Controller nodes in the cluster, unless you are using a dual-core fabric design. Create one zone for each host fibre-channel port. In a disk zone, the SAN Volume Controller nodes identify the storage systems. Generally, create one zone for each storage system. Host systems cannot operate on the storage systems directly; all data transfer occurs through the SAN Volume Controller nodes. If you are using the Metro Mirror and Global Mirror feature, create a zone with at least one port from each node in each cluster; up to four clusters are supported.

Figure 1 shows an example of a host zone. Figure 2 shows an example of a cluster zone. Figure 3 shows an example of a disk zone.

Figure 1. Example of a SAN Volume Controller host zone

This figure shows an example of a host zone.

Figure 2. Example of a SAN Volume Controller cluster zone

This figure shows an example of a cluster zone.

Figure 3. Example of a SAN Volume Controller disk zone

This figure shows an example of a disk zone.

A cluster of SAN Volume Controller nodes is connected to the fibre-channel fabric and presents virtual disks (VDisks) to the host systems. You create these VDisks from units of space within a managed disk (MDisk) group. An MDisk group is a collection of MDisks that are presented by the storage systems (RAID controllers). The MDisk group provides a storage pool. You specify how each group is created, and you can combine MDisks from different manufacturers' controllers in the same MDisk group. However, to optimize the use of resources, ensure that all MDisks in an MDisk group have similar performance characteristics.

Note: Some operating systems cannot tolerate other operating systems in the same host zone, although you might have more than one host type in the SAN fabric. For example, you can have a SAN that contains one host that runs on an IBM® AIX® operating system and another host that runs on a Microsoft® Windows® operating system.

All communication between SAN Volume Controller nodes is performed through the SAN. All SAN Volume Controller node configuration and service commands are sent to the cluster through an Ethernet network.

Each SAN Volume Controller node contains its own vital product data (VPD). Each cluster contains VPD that is common to all the SAN Volume Controller nodes in the cluster, and any system, with the correct access authority, that is connected to the Ethernet network can access this VPD.