SAS2 - OPEN TIMEOUT

Larry Chen Larry_Chen at pmc-sierra.com
Wed Jan 9 13:35:21 PST 2008


Formatted message: <A HREF="r0801092_f.htm">HTML-formatted message</A>

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 at us.ibm.com] 
Sent: Wednesday, January 09, 2008 8:15 AM
To: Larry Chen
Cc: t10 at 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 at us.ibm.com
http://www-03.ibm.com/servers/storage/ 
"Larry Chen" <Larry_Chen at pmc-sierra.com> 
Sent by: owner-t10 at t10.org 
01/08/2008 03:00 PM 
To
<t10 at 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). 



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