Qualstar 501440 Rev. G Installation And Operation Manual
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Contents
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4.7 Configuring the Fibre Channel Loop IDThe Id Mode must be configured for either “Soft” or “Fixed” addressing. Using “Soft”addressing, the Fibre Channel Option connects to an arbitrated loop using the firstavailable AL_PA, scanning from the highest valid address to the lowest. Using “Fixed”addressing, the user selects a specific arbitrated loop address (AL_PA) to connectwith. If the selected address is not available, the Fibre Channel Option will connectwith the first available address it finds. The use of “Soft” or “Fixed” addressing isbased on the user’s installation requirements.Soft addressing can be configured when address conflicts are not likely. If the FibreChannel Option is connected directly to the computer’s HBA (Host Bus Adapter), theselection of a specific Loop Id is not usually required. For example, Emulex HBA driv-ers scan for an available address starting from the low Fibre Channel address range.The FCO begins scanning for an available address starting from the high Fibre Chan-nel address range. This avoids address conflicts and the FCO Loop Id will be assignedthe same value each time it is restarted.Hard addressing should be configured if address conflicts can occur. This can happenif the FCO is connected to a Fibre Channel Hub. Since many HBA drivers map the Fi-bre Channel Loop Id to a SCSI Bus/Target address, this mandates that the FibreChannel Loop Id be very stable, and cannot be allowed to change if the system is sim-ply restarted. This might happen if soft addressing were used and the Fibre ChannelOption found its previous address taken. Selecting a fixed address is a way to preventthe FCO Loop Id from changing if the system is restarted.If the computer’s HBA uses the World Wide Port Name (WWPN) convention insteadof the Loop Id to map to a SCSI Bus/Target/Lun address, the value of the Loop Id is nolonger important. The WWPN is always unique and consistent under all conditions. Inthe future, all addressing will likely use the WWPN.C••••••Fibre•Channel•DeviceId Mode 0: SOFTLoop Id 0: nnnTopology 0: LOOPC••••••Fibre•Channel•Device Left•Device RightL Id Mode 0: SOFTL Loop Id 0: nnnL Topology 0: LOOPR Id Mode 0: SOFTR Loop Id 0: nnnR Topology 0: LOOPSingle Bay or one sideof a Dual Bay LibraryDual Bay Librarywith two FCO’sThe Configuration\Fibre Channel menu panel displays the SCSI device in-terface and configures the Fibre Channel Interface to host. The menu sets the FibreChannel Option host topology. The “Topology” has two selections, LOOP and FABRIC.The LOOP selection configures the Fibre Channel Option for Arbitrated Loop (FC-AL)operation. The FABRIC selection configures the Fibre Channel Option for Switch Fab-ric (FC_SW) operation. If the mode is LOOP, the Id Mode and Loop Id entries areavailable.501440 Rev. J FCO Type C Installation 4-17 |
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