McDATA 3000 manual 10-5

LUN Discovery

LUN Refresh

Dynamic LUN

Mapping

Static LUN Mapping

Dynamic Target LUN Discovery and LUN Mapping

Target discovery is not aware of device type or available LUNs on the discovered target.

A maximum of 32 devices can be discovered or configured unidirectionally per I/O pair. Available bandwidth should be considered for concurrent operation of the drives.

As targets are discovered, those targets will be queried for available devices via LUN discovery. A configurable number of LUNs (maximum of 32, default is 8) will be attempted to be discovered for each discovered remote target. These devices will be mapped on the Edge target LUN field with the dynamic LUN mapping rules. LUN discovery will filter remote LUNs based upon the device type field in the inquiry response. Only device types of tape and changers will be added to the host LUN table. LUN Discovery is only done to newly discovered remote targets.

Remote targets will be scanned for newly available LUNs whenever the target Edge is rebooted or the user issues the “refresh” command via the ttag user interface. If any new LUNs are discovered, those LUNs will be added to the host LUN table, if an open host LUN field is available. Existing LUNs already discovered to any remote targets will not be rescanned. LUN refresh will not remove a remote device which is no longer available.

The Edge target will discover, via Edge initiator target discovery, available remote targets. The Edge target will map discovered targets based upon WWNs on a first learned basis. The discovered targets will fill the Edge target LUNs from lowest (1) to highest (x). The mapped LUN will be bound to the associated WWN and any change in remote target portid will be dynamically learned. The WWN and associated Edge target LUN will also be stored onto disk which will provide consistency on the Edge target LUN mapping across resets and power downs.

The Edge target may be configured for a specific Edge target LUN to be bound to a designated remote target WWN. If a remote target is statically configured, all LUNs to be mapped to that remote target must be statically configured and should be mapped consecutively from lowest to highest. Any Edge target LUN not statically configured will be discovered via dynamic LUN mapping.

FC/SCSI Tape Pipelining 10-5

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