Virtual TapeServer SCSI-to-FC Adapter User Manual

7-13
Chapter 7: Using the Serial/Telnet Interface
– Link-up Events discovers both the ports and the devices behind the ports for the first link-
up event (which is the first reboot of the VT5900-SA). Subsequent link-up events will
only discover the ports and not the devices behind the ports.
Manual Discovery is the default selection and sets discovery of new devices to only occur
after the user selects the Refresh Device Display option from the Display Attached Fibre
Channel Devices menu, located under Main Menu > System Utilities > System Statistics >
Display Fibre Channel Protocol Status.
• Select 6 to toggle Buffered Tape Writes to enabled or disabled. Buffered Tape Writes is an
option designed to enhance system performance. By returning status on consecutive write
commands prior to the tape device receiving data, Buffered Tape Writes remove the latency of
waiting for responses from the tape device. In the event that data does not transfer correctly for
any reason, the VT5900-SA will return a check condition on a subsequent command.
Commands other than Write(6) are not issued until status is received for any pending write.
Also, status is not returned until the device completes the command. For instance, when a
synchronizing command is sent to a drive, such as sending a Write File mark, a good status
means all prior commands have been successfully completed and data has been successfully
written to the medium. This is appropriate for such tasks as file backup/restore.
• Select 7 to change the Tape Backup Queue Depth. For the VT5900-SA Virtual TapeServer
SCSI-to-FC Adapter, select a value of 0 through 10.
• Select 8 to change the Default Map Value. This can be Indexed, Auto-assigned, or SCC. The
default setting is Auto-assigned. The FC Auto-assigned map contains all the SCSI devices that
are attached to the VT5900-SA. When a new initiator contacts the VT5900-SA through the
selected port, it will be able to access the devices that are in this map by default.
• Select 9 to edit the FC override settings. When this option is selected, the following menu
appears.
Note: SCSI devices attached to a Fibre Channel port must be mapped as
sequential FC LUNs starting at LUN number 00. Skipping LUN numbers is
not recommended when mapping FC LUNs because FC Discovery stops
the discovery process whenever an empty LUN position is found.
Note: If the application requires confirmation of individual blocks being
written to the medium, such as audit trail tapes or log tapes, this option
should be disabled.