We have a tape library that we'd like to integrate into our SAN environment via a bridge (Dell Power Vault 35F).
How does a bridge translate SCSI device IDs to FC WWNs? Will each tape drive be assigned a WWN?
Thanks in advance.
The Power Vault 35F is most likely a re-branded Chaparral or Crossroads bridge. The bridge acts like a SCSI initiator on the SCSI side and an FC target on the FC side. "SCSI targets are selected by mapping the appropriate values into the FCP LUN field and correlating a Fibre Channel LUN value to a SCSI Bus:Target:LUN value. The Power Vault 35F acts as a single initiator on each SCSI bus, defaulting to ID 7. All commands passed through to a SCSI bus originate from this SCSI ID."
One thing to remember is that there may be two mode of operation in assigning SCSI IDs to the tape robot and drives in a library behind the bridge. You can choose auto mode, which automatically assigns IDs on boot or you can hard map them in the address-mapping table in the bridge. Use the latter, since auto-mapping IDs may reassign SCSI numbers and that would wreak havoc on your backup program! I have seen many sites with this issue. You use the bridge to create persistent bindings on the hardware side so the host OS does not get confused when scanning for SCSI targets.
You can get more information on how to configure the 35F from Dell's Web site at: href=http://docs.us.dell.com/docs/stor-sys/spv35f/
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This was first published in February 2002