Reset Processing - Fujitsu MAX3073NC - SCSI,80, Dell DC961,Hard Drive Scsi Logical Interface Specifications

Command Processing
1.7.6

Reset processing

The INIT can reset the SCSI bus with following.
•
RESET condition
•
TARGET RESET message
•
CLEAR TASK SET message
•
ABORT TASK SET message
•
ABORT TASK message
The RESET condition resets all the SCSI devices connected on the same SCSI bus. The IDD is
initialized to the same state as when its power is switched on by the RESET condition, with the currently
executed command as well as all the commands in the queue cleared.
The TARGET RESET message resets only specific SCSI device (TARG) selected by the INIT, and can
initialize that TARG to the same state as when its power is switched on. However in a multi-initiator
environment, caution concerning clearing of commands issued by other INITs is necessary.
The CLEAR TASK SET message clears all commands that the IDD is executing or queuing. The
previously set environment and conditions, such as MODE SELECT parameters, are not changed.
An INIT which wants to clear only specific commands it has issued itself must use an ABORT TASK
SET message or an ABORT TASK message. In this case, the INIT generates an ATTENTION condition
at the desired point in time if that command is currently being executed on the SCSI bus, then sends the
ABORT TASK SET message to the TARG. Also, if there is a disconnect in effect, after the INIT selects
the TARG, an ABORT message, in the case of an untagged command, or an ABORT TASK message, in
the case of a tagged command, is sent following an IDENTIFY message which specifies the object logical
unit, or the INIT waits until a reconnection request occurs, then sends an ABORT TASK SET message or
ABORT TASK message. In the case of an ABORT TASK SET message, only the commands issued
previously in the logical unit specified at that time by the INIT that issues the ABORT TASK SET
message (currently being executed or queuing) are cleared and there is no influence on the other
commands.
When an ABORT TASK message is received, only the command issued to the logical unit specified at
that time by the INIT which issued the ABORT TASK message is cleared, and there is no influence on
the other commands. No status or TASK COMPLETE message concerning commands cleared in this
processing is reported.
In particular, in the case of clearing of a write operation command for writing to the disk media which is
currently being executed, the IDD stops processing of that command as shown in Table 1.6. The case of
halting an overlapping command that is currently being executed (see Section 1.7.1) is the same. The
INIT must determine the complete completion state and if necessary, must execute data recovery
processing.
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