A SAS-2 SMP initiator does not have anything defined to enforce that response time from an SMP target.... it is supposed to be tolerant of arbitrary SMP response time still, for the very reason of backward compatibility.

Likewise, there isn't a definition in SAS-2 SMP target to enforce the 100us time limit for SMP initiator to send the SMP REQUEST frame in the connection.

However, it just "works out" to having bounded SMP performance when you have SAS-2 compliant SMP devices on both sides of the connection.

Brian Day

LSI Corporation

From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Fore, Chris
Sent: Monday, April 07, 2008 12:34 PM
To: t10@t10.org
Subject: Legacy compatibility for the SAS-2 SMP_RESPONSE frame time limit?

SAS-2 added a time limit for SMP request completion of 1900us (see sas2r14 7.18.1).

Would anyone care to comment regarding expected behavior when a SAS-2 SMP initiator is connected to a SAS-1.1 compliant SMP target that does not adhere to this time limit?

R. Chris Fore
Senior Engineer
RAID Engineering

NetApp
919.476.5155 Direct
Chris.Fore@netapp.com
www.netapp.com