Subject: RE: SAS connection timing
Date: Tue, 1 Apr 2008 09:49:05 -0600
From: "Day, Brian" <Brian.Day@lsi.com>
To: "Kevin D Butt" <kdbutt@us.ibm.com>, <t10@t10.org>
X-Message-Number: 8674
Formatted message: HTML-formatted message

Kevin...
No...  there are not timing requirements in the SAS spec to limit how
long an end device (initiator or target) may reject connection requests
with OPEN_REJECT(RETRY).  I think is is the scenario you were asking
about.
There are other conditions which would cause the I_T Nexus Loss timer to
expire, but those of course are generally relative to not getting the
connection request (OPEN frame) actually "routed" to the intended end
device.  OPEN_REJECT(RETRY) does not cause I_T Nexus Loss.
I'll point out that there is an Initiator Response Time timer defined,
but that is limitted to timing how long it is taking an initiator to
provide write data back to a target.   If the initiator does not provide
some write data withing this time limit, then the target may start
aborting that command.	For more info on this time, check out section
9.2.6.3 of the r14 draft spec.
Also as side note... the addition of the "CONTINUE AWT" bit is an
attempt to help devices contiunue to get their work done when receiving
an OPEN_REJECT(RETRY), so that they don't always go back to lowest
priority.
Brian Day
LSI Corporation
________________________________
From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Kevin D
Butt
Sent: Monday, March 31, 2008 3:44 PM
To: t10@t10.org
Subject: SAS connection timing
Is there any requirements related to how long it can take to allow an
OPEN when in the middle of a SCSI transfer? 
e.g., Read command 
target tries to OPEN a connection with the initiator port to transfer a
frame.	The initiator port doesn't accept the OPEN.  How long is can the
initiator port not accept the OPEN (e.g., to perform flow throttling)? 
Thanks, 
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/