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User’s Guide 21020285 D
Chapter 7 Board-control Commands
Unit Options (08H) Page 7 - 19
Disconnect Time-out
If you have enabled SCSI bus Disconnect/Reconnect with the General Options
command (DIS bit of Select Flags is set), this field selects — for the specified
unit — the amount of time the adapter will wait for a reconnect. If a reconnect
does not occur within the time defined, the adapter will post a time-out error
(1FH) in the appropriate command Status Block.
The time appropriate for a disconnect depends on the action and the unit
performing the task (seeks, rewinds, etc.). For this reason, the Disconnect Time-
out value is tailored per unit with a latitude of 100 milliseconds to almost two
hours. You may also choose the option of no time-out for this unit. In that case,
the device or SCSI bus must be reset to recover from the failure.
0 ⇒ No time-out occurs; SCSI bus or device must be reset to clear a failure.
Each increment ⇒ 100 milliseconds.
Note
The sequentially
recorded nature of tape
media is such that
positioning for retries
requires extra
commands. For this
reason, do not enable the
retry function for SCSI
tape devices.
Retry Limit
If retries are enabled in the Retry Control field, (discussed next) this field
specifies the maximum number of retries to attempt before reporting an error.
Once the retry limit is reached, the error condition reported on the last retry is
returned in the Status Block.
You must provide a value in this field or retries will not occur even if enabled
(in the Retry Control field).
Retry Control
This field is used to particularize the retry operation for this unit. This field
allows you to select the type of errors to retry and how they are reported.
INT Issue Interrupt - When ISB bit is set, allows you to select whether the
adapter posts an interrupt for retry Status Block(s) when returned. Valid only
when ISB bit is set.
0 ⇒ Do not interrupt for retry Status Block(s).
1 ⇒ Interrupt when retry Status Block(s) returned.
ISB Issue Status Block - Allows you to select that a Status Block be returned
for each command retry performed. Enabling this will cause multiple Status
Blocks to be returned for a command that requires retries.
0 ⇒ Do not issue a Status Block for each retry.
1 ⇒ Issue a Status Block for each retry.
RPE Retry Parity Errors - Allows you to retry SCSI commands that failed
with a parity error.
0 ⇒ Do not retry for parity errors.
1 ⇒ Retry parity errors.
BITS
76543210
0 0 0 RBE RCE RPE ISB INT
Table 75: Retry Control