After the STP connection is established, the host and device are just following normal SATA protocol; frame transmission can go in either or both directions during the connection.  X_RDY and R_RDY are used to coordinate frame transmission.  If both want to send a frame, they both send X_RDY.  The host always defers in this case and sends R_RDY, allowing the device to send its frame first.  The host can try again after that frame is finished.

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Rob Elliott, HP Industry Standard Server Storage



From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Marian Lakov
Sent: Monday, May 26, 2008 11:48 AM
To: t10@t10.org
Subject: Opening a STP connection

Hi,
 
I've seen a situation where a STP Initiator opens a connection to STP Target/SATA Bridge. The STP Target sends back OPEN Accept and then starts sending DATA or DMA Setup or DMA Activate FISs. As per SAS-2:
 
7.12.2.1 Connection request

The OPEN address frame (see 7.8.3) is used to open a connection from a source port to a destination port using one source phy and one destination phy.

If the STP Target is the Source Port shouldn't the connection be opened from the STP Target? Is it acceptable the STP Initiator to open a connection if the STP Target will be the source port?
 
Thanks,
Marian
 
________________________
Marian Lakov
Systems Engineer
Xyratex
1804 Centre Point Circle, Suite #112
Naperville, IL 60563
Office:  630-364-7600
Fax:     630-364-7601
marian_lakov@us.xyratex.com