This MIB instrumentation is for managing Fibre
Channel (FC) SAN Device Virtualization (SDV) 
solution on Cisco Fibre Channel devices.

Glossary of the terms used in this MIB:
---------------------------------------
Config Commit  - User initiated action that triggers
            commiting of configuration to local
            device/fabric. Eg. CFS based config 
            'commit' as described in CISCO-CFS-MIB.
            
Domain         - The highest or most significant 
            hierarchical level in the three-level
            FC addressing hierarchy.
            
Device Aias    - is a string which can be used to alias a
World Wide Name (WWN).
            
FCID           - Fibre Channel Address ID. A 24 bit Fabric
            unique address identifier.
            
FCNS           - Fibre Channel Name Server.
            
Initiator      - The system component that originates an
            I/O command over an I/O bus or network.
            
NWWN           - WWN associated with FC node.
            
PWWN           - WWN associated with FC port.

Real Device    - A hardware entity which includes Link
            Control facility. It is directly
            connected to a FC fabric and acts as
            originator/responder or both.
            
RSCN    	   - Registered State Change Notification.
            RSCN Notifications are sent to Nx_ports
            and other switches to notify that an
            event has occurred.
            
SW_RSCN        - Switch Registered State Change
            Notification. SW_RSCN Notifications are
            sent to neighbouring switches in a
            fabric to notify that an event has
            occurred.
            
SCSI           - Acronym for Small Computer System
            Interface.
            
Target         - The system component that receives a
            SCSI I/O command command.
            
Virtual Device - The virtual initiator/target having its
(VD)          own device identity and proxies a Real
            Device (Initiator/Target) in a FC fabric.

VT             - Virtual Target.   

VI             - Virtual Initiator.

Virtual Domain - A logical Domain partition in a FC fabric
            within which a Virtual Device exists.            
                        
VSAN           - Virtual Storage Area Network, similar
            to a VLAN.

WWN            - Wide Name (WWN) associated with
            a Fibre Channel (FC) entity. A 64 bit
            identifier, with a 60 bit value preceded
            with a four bit 
            Network_Address_Authority_Identifier,
            used to identify physical entities in
            Fibre Channel.
 
The primary motivation for SAN Device Virtualization
is the High availability of storage disk arrays with
no downtime. Redundancy is achieved by duplication
of information and hardware to ensure secondary
device can take over the function of a primary
device when the latter fails. The initiators
(servers) perform I/O to the primary target. 
The secondary target is kept in sync to have a
mirrored copy of the primary target by a replication
mechanism. In the event of a disruption to primary
target, all I/O must be immediately re-routed to 
secondary target so that services running on 
initiators remain un-interrupted. The SDV solution
resides on a Cisco FC Switching Device. The target 
failover is achieved by presenting a virtual proxy
target to initiator with the SDV acting as a conduit
for creating and deleting the proxy (virtual)
target on demand. The Virtual Target or in general
Virtual Device can virtualize (proxy) set of Real
Devices with one Real Device actively mapped as the
primary mapping and the rest as secondary mappings.

                                  WWN2,FCID2
                                   _____
                                  |     |
             [Switch Fabric]     /| RT1 |
             '''''''''''''''    / |_____|
WWN1,FCID1    '             '   /  [Primary Real
  ____       '  WWN4,FCID4 '  /    Target Device]
 |    |      '  +~~~~~~~+__'_/ 
 | I  |->--->'->|  VT   |__'_
 |____|      '  +~~~~~~~+  ' \     
[Real Host   '             '  \{On Fail-Over}
(Initiator)] '             '   \   WWN3,FCID3
             '''''''''''''''    \  _____
            [VT: Virtual Target] \|     |
                                  | RT2 |
                                  |_____|
                                  [Secondary Real
                                   Target Device]
                                   
              -<< Fig 1 >>-

In the above figure (Fig 1), 'Switch Fabric'
presents the Virtual Target 'VT' as a proxy device
for real targets 'RT1' and 'RT2'. The Host/Initiator
'I' can discover a virtual target VT and does not
see real targets RT1 and RT2 as accessible targets.
The Virtual Target VT is configured on the switch
and maps to one real target as a primary mapping.
The Initiator performs I/O with VT. When the primary 
target RT1 fails, the secondary real target RT2 can
take over. For the Initiator, failover/migration is
transparent and continues to perform I/O with VT.

 ___                   ____                  ____
|   |-->--[I->VT]-----[    ]---->--[I->T]---|    |
| I |                 [ VT ]                | RT |
|   |                 [    ]                |    |
|___|--<--[I<-VT]-----[____]----<--[I<-T]---|____|

[Initiator]             [Virtualized           [Real
                      Target]                Target]

              -<< Fig 2 >>-

When the Initiator 'I' performs I/O with VT, the
SDV enabled switch performs FCID address translation
to route FC frames to the real target RT (refer
Fig 2). The I->VT frames are translated as I->T. 
The T->I frames are translated as VT->I. The SDV
manages VT so that other devices (in the same zone)
perceive it as just another device in the fabric.

The cFcSdvVirtDeviceTable is table of Virtual Devices.
The cFcSdvVirtRealDevMapTable is a table of mapping
elements.

A Virtual Device is represented by a row in the
cFcSdvVirtDeviceTable, and if its value of 
cFcSdvVdRealDevMapList has the value of zero,
then the Virtual Device is not currently mapped to
any Real Devices. Otherwise, the Virtual Device is
mapped to the set of Real Devices with each Real
Device identified by the instance indentifier value
of cFcSdvVirtRealDevMapIndex.