HP ML370 Serial Attached SCSI storage technology, 2nd Edition - Page 15

Figure 13. A group of zoning-enabled SAS expanders (ZPSDS) can be configured to allow only certain end devices to see each other. Zoning methodology The SAS-2 standard permits zoning, a secure zoning method that uses the unique ID number of each expander phy. In zoning, each port of a zoning expander is assigned to a zone group, and any device attached to one of the ports becomes part of that respective zone group. By default, all devices within a zone group can interact with each other. The permission table in the expander controls access between devices in different zone groups. If an attached device changes, the expander may be configured to set the zone group to 0 (no access), which allows an address-resolved-like policy to be implemented. For example, if a particular SAS device address needs to have certain permissions and the device is moved to a different expander in the fabric, then the zone manager can reprogram the zone group at the new location. Zoning is ideal for small topologies, server blade enclosures, and clustering applications. Zone management A zone manager is responsible for configuring each zone. As shown in Figure 14 (top), the zone manager can control a zone by using an end device that has a SAS port connected to one of the zoning expanders. The zone manager can also control a zone through a sideband interface (such as Ethernet) on one or more zoning expanders (Figure 14 bottom). 15