This discussion raises a more basic question for me: does the term, "open connection timeout" mean the same thing as "Connection Timeout Timer expires"? The term, "open connection timeout" occurs only once in the entire standard (in subclause 4.5), whereas the term "Open Timeout Timer expires" occurs 7 times in the text. The latter is what happens when the attached phy doesn't send an ARB for 1ms. There is a corresponding confirmation from the link layer to the port layer, "Open Timeout Occurred", which sounds a lot like "open connection timeout", but is not explicitly equivalent.
 
Subclause 8.2.2.3.2 PL_OC2:Overall_Control state establishing connections states:
If this state receives a Retry Open (No Destination) or a Retry Open (Open
Timeout Occurred) message and an I_T Nexus Loss timer has not been created for
the destination SAS address (e.g., an SSP target port does not support the I_T
NEXUS LOSS TIME field in the Protocol-Specific Port mode page or the field is
set to 0000h), then this state shall process the Retry Open message as either a
Retry Open message or an Unable To Connect message. This selection is
vendor-specific.
Indicating it may be optional whether to retry or not. This behavior is at the port level, so it applies not only to initiator ports, but also to target ports and expander ports. I could see different port types needing to handle this differently.
 
Incidently, a self-configuring expander has a way to report this condition to a management application, "Connection request failed: Open Timeout timer expired" (see table 235 in subclause 10.4.3.5.4 Self-configuration status descriptor).
 
Bob Sheffield
LSI Corporation

From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Larry Chen
Sent: Wednesday, January 09, 2008 2:35 PM
To: Kevin D Butt
Cc: t10@t10.org
Subject: RE: SAS2 - OPEN TIMEOUT

 

IMO, Timeouts are more serious than OPEN_REJECTs (and NAK, SCSI Busy and Full Queue) Responses.

 

If Timeouts are _not_ reported to the host driver and/or the diagnostic monitoring code then the problem can not

be detected and rectified Via a FRU swap.

 

From: Kevin D Butt [mailto:kdbutt@us.ibm.com]
Sent: Wednesday, January 09, 2008 8:15 AM
To: Larry Chen
Cc: t10@t10.org
Subject: Re: SAS2 - OPEN TIMEOUT

 


 I do not see a reason to distinguish an open timeout from the other errors.  Unless there is a very good reason, I would prefer to leave the text as is.  It seems to me that we should retry open timeouts, since it may work the next time.  Also, the point of doing recovery operations is to mask errors (so that the job can continue), so that does not seem like a good reason to stop attempting the recovery.  

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/

"Larry Chen" <Larry_Chen@pmc-sierra.com>
Sent by: owner-t10@t10.org

01/08/2008 03:00 PM

To

<t10@t10.org>

cc

 

Subject

SAS2 - OPEN TIMEOUT

 

 

 




Is there any mechanism in place to _exclude_ OPEN TIMEOUT from being retried (see
RED font below for details). I think there is a danger of masking out errors if OPEN TIMEOUT
Is blindly retried.
 
 
---
 
4.5 I_T nexus loss
When a SAS port receives OPEN_REJECT (NO DESTINATION), OPEN_REJECT (PATHWAY BLOCKED),
OPEN_REJECT (RESERVED INITIALIZE 0), OPEN_REJECT (RESERVED INITIALIZE 1), OPEN_REJECT
(RESERVED STOP 0), OPEN_REJECT (RESERVED STOP 1), or an open connection timeout occurs in
response to a connection request, it shall retry the connection request until:
a) the connection is established;
b) for SSP target ports, the time indicated by the I_T NEXUS LOSS TIME field in the Protocol-Specific Port
mode page (see 10.2.7.4) expires; or
c) the I_T nexus loss timer, if any, expires (see 4.7.1, 8.2.2.1, 10.2.7.4, and 10.4.3.17).