Technical data

Brocade Communications Systems, Inc. Page 31 of 48
member of a zone under hard zoning, configured by an administrator, before a host bus adapter can access a storage
device.
Zoning works by checking each frame before it is delivered to a zone member and discarding it if there is a zone
mismatch. The TOE monitors HBA communications and blocks any frames that do not comply with the zone
configuration. Zoning prevents users from even discovering the existence of unauthorized target devices.
A zone is a region within the fabric where a specified group of fabric-connected devices (called zone members) have
access to one another. Storage devices not explicitly defined in a zone are isolated, and host bus adapters in the
zoned fabric do not have access to them.
• A group of one or more zones is called a zone configuration.
• The complete set of all zone members defined in a fabric is called the defined zone configuration.
• Zoning configuration procedures change zone objects in the defined configuration. When a configuration is
enabled by an administrator, it becomes the effective zone configuration. The effective zone configuration
is restored after a TOE reboot. This is also known as the active zone configuration.
• A copy of the defined zone configuration (plus the name of the effective zone configuration) can be saved
by an administrator. The resulting saved zone configuration is restored after a switch reboot. If an
administrator makes changes to the defined zone configuration but does not save them, there will be
differences between the defined zone configuration and the saved zone configuration.
• A default zone is a zone that contains all ports that are not members of any zone in the active zone set.
A zone object is either an HBA or a disk. Any zone object connected to the fabric can be included in one or more
zones. Zone objects can communicate only with other objects in the same zone. For example, consider the figure
below, which shows:
• Three zones are configured, named Red, Green, and Blue.
• Server 1 can communicate only with the Loop 1 devices.
• Server 2 can communicate only with the RAID and Blue zone devices.
• Server 3 can communicate with the RAID device and the Loop1 device.
• The Loop 2 JBODs are not assigned to a zone; no other zoned fabric device can access them.
The TOE determines whether or not to allow an HBA access to a storage device by comparing zone memberships. If
access is permitted, the HBA is subsequently permitted to issue FC/FCIP-protocol commands that correspond to
disk read and write operations. If access is not permitted, a rejection command is returned to the HBA and any
subsequent read or write operations from that HBA are discarded by the TOE.
When a host bus adapter performs a read or a write after the HBA has established a connection with a storage device
using the TOE according to the SAN Fabric SFP, the HBA either breaks data blocks up into multiple data frames (in
the case of a block-write operation) before sending the information to the TOE, or reassembles data frames into