Does ABORT TASK clear CA

George_Penokie at tivoli.com George_Penokie at tivoli.com
Thu May 10 09:14:19 PDT 2001


* From the T10 Reflector (t10 at t10.org), posted by:
* George_Penokie at tivoli.com
*
I was requested to look into the wording in the standards to see what the
standards say should happen to a CA after an ABORT TASK message occurs. I
have discovered that both SAM-2 and SCSI-2 strongly imply that a CA is not
cleared if an ABORT TASK message occurs. The references from the standards
that lead me to this conclusion are below.  The problem is I believe most
devices will clear the CA on receipt of an ABORT TASK message.

>From SCSI-2

Section 7.6 Contingent Allegiance Condition states:

"The contingent allegiance condition shall exist following the return of
CHECK CONDITION or COMMAND TERMINATED status. The contingent allegiance
condition shall be preserved for the I_T_x nexus until it is cleared. The
contingent allegiance condition shall be cleared upon the generation of a
hard reset condition, or by an ABORT message, a BUS DEVICE RESET message,
or any subsequent command for the I_T_x nexus. While the contingent
allegiance condition exists the target shall preserve the sense data for
the initiator."

Section 7.8.2 Tagged Queuing

"The first method allows the execution of tagged I/O processes to resume
when the contingent allegiance or extended contingent allegiance condition
is cleared. The target returns BUSY status to other initiators while the
contingent allegiance or extended contingent allegiance condition exists.
During this time, all tagged I/O processes are suspended. All I/O processes
used for recovery operations shall be untagged. The queue may be modified
by removing all or selected I/O processes from the queue as part of the
recovery procedure."

>From SAM-2 rev 17

Section 6.3 ABORT TASK SET

"A contingent allegiance (NACA equals zero) shall be cleared by the ABORT TASK SET function."

Section 6.5 CLEAR TASK SET

"A contingent allegiance (NACA equals zero) shall be cleared by the CLEAR TASK SET function."

Section 6.2 ABORT TASK

States nothing about CA.

Bye for now,
George Penokie

Dept 2C6  114-2 N212
E-Mail:    gpenokie at tivoli.com
Internal:  553-5208
External: 507-253-5208   FAX: 507-253-2880

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