23
SCSI SWITCH (FOR AS/400
®
)
Front Panel Switch
The front panel manual switch can override the software and force tape drive
ownership to the other host without having to power cycle the SCSI Switch.
The front panel switch always takes precedence over any host software
“ownership” of the tape drive.
Table 4-2. Front-Panel Switch.
Position
Mode
Host A
Host A always “owns” the tape drive. The tape drive cannot be
released by software for use by Host B.
Auto
Normal position. Either host can arbitrate for use of the tape drive.
Once a hosts “owns” a tape drive it is free to release it at any time.
Host B
Host B always “owns” the tape drive. The tape drive cannot be
released by software for use by Host A.
There is a six-second delay from the time the front-panel switch position is
changed to the time the SCSI Switch responds to the change. This delay
allows time to recover from an unintentional switch change. Modifying the
position of the manual switch should be considered a last resort in an error-
recovery procedure, since it can reset the SCSI Switch and tape drive, and
can abnormally terminate a process using the tape drive.
Table 4-3
shows the results of changing the position of the manual switch.