SAM R14, ABORT TASK for untagged tasks
73632.1106 at compuserve.com
Tue Aug 9 10:16:43 PDT 1994
Clause 5.1 of SAM says that the ABORT TASK function is optional for
untagged tasks. This is contrary to SCSI-2.
SCSI-2 has two mechanisms for aborting tasks: The ABORT TAG message and
the ABORT message for a fully identified task of any type. These are BOTH
ABORT TASK FUNCTIONS.
SAM does not specify ABORT TAG only. It specifies that the ABORT TASK
task management functions identifies the task to be aborted. IN SIP, that
can always be accomplished by fully identifying a task (tagged or
untagged) and sending the ABORT message. SCSI-2 for tagged tasks
permitted the ABORT TAG message and allowed it to be applied, optionally,
to untagged tasks.
SAM has the ABORT TASK function confused with the ABORT TAG and ABORT
messages. What SAM says in revision 14 is that it may be impossible to
abort an untagged task if the logical unit does not support the ABORT TAG
message in SIP. This is incorrect.
Each protocol must identify how any task, individually, is capable of
being aborted. For SIP, there is one guaranteed way, and one guaranteed
only for tagged tasks. Therefore, SIP and all other protocols must
support the ABORT TASK task management function for all tasks. SIP just
has two ways which are an implementation choice to use.
This must be fixed in SAM. If it is not fixed now, it will cause a second
public review to have it fixed later.
More information about the T10