Dynamic target lun discovery and lun mapping, Overview, Target discovery – McDATA ULTRANETTM EDGE STORAGE ROUTER 3000 User Manual
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McDATA UltraNet Edge 3000 User Guide
Dynamic Target LUN Discovery and LUN Mapping
The server UltraNet Edge 3000 may also be statically configured for a
specific UltraNet Edge 3000 target LUN to be bound to a designated
remote target WWN.
Dynamic Target LUN Discovery and LUN Mapping
The following sections provide an overview of target and LUN
discovery and both dynamic and static mapping.
Overview
When an Edge Fibre Channel interface is configured for FCP, it may
be configured as an Edge target, an Edge initiator or both. The Edge
initiator actively connects to device targets. The Edge target passively
connects to host initiators.
The Edge target and Edge initiator maintain arrays of I_T_L
connections based upon SCSI IDs. In implementing FCP, the port ID
or alpa is used in place of the SCSI ID to maintain the SCSI ULP
functionality.
To host initiators, the Edge target appears as a single target with
multiple LUNs. When LUN 0 is configured in Emulate mode, it will
appear as a device type controller. When LUN 0 is configured in
Passthru mode, it will represent an actual remote device. In either
case, the Report LUNs command will be handled locally in the Edge
attached to the host and the response will indicate all available host
LUNs.
The Report LUNs command is handled by the Edge target and
reflects the number of configured LUNs (SCSItoSCSIdataPath). The
response to a Report LUNs command merely indicates the number of
LUNs available. This information is forwarded to the host regardless
of the number or the state of remote targets.
The number of LUNs configured will be 8 (not counting LUN 0) by
default with a max of 32.
Current FCP Edge target to FCP Edge initiator is strictly
point-to-point.
Target Discovery
The Edge initiator will dynamically discover available targets and
actively login/logout of those targets as conditions warrant. The
WWN and associated port IDs of each currently logged in target, is
forwarded to the associated Edge target on a regular timed interval.