LOCAL RECONNECTION ATTEMPTS FOR SERIAL ATTACHED SMALL COMPUTER SYSTEM INTERFACE EXPANDERS
Methods and structure for local reconnect attempts via a Serial Attached Small Computer System Interface (SAS) expander. The system includes a SAS expander, which includes a physical link (PHY) that is able to transmit an OPEN Address Frame (OAF) to a coupled SAS device, and to receive an OPEN_REJECT (RETRY) from the coupled device in response to the OAF. The SAS expander also includes a controller that is able to block transmission of the OPEN_REJECT (RETRY) out of the expander in order to preserve a signaling pathway established for the OAF, and to retransmit the OAF to the coupled device via the PHY.
1 . A system comprising:
a Serial Attached Small Computer System Interface expander, comprising:
a physical link operable to transmit an OPEN Address Frame to a coupled Serial Attached Small Computer System Interface device, and to receive an OPEN_REJECT (RETRY) from the coupled device in response to the OPEN Address Frame; and
a controller operable to block transmission of the OPEN_REJECT (RETRY) out of the expander in order to preserve a signaling pathway established for the OPEN Address Frame, and to retransmit the OPEN Address Frame to the coupled device via the physical link.
2 . The system of claim 1 , wherein:
the coupled device comprises an end device, and
the controller is further operable to block transmission of the OPEN_REJECT (RETRY) in response to determining that the physical link is directly attached to the end device.
3 . The system of claim 1 , wherein:
blocking transmission of the OPEN_REJECT (RETRY) comprises preventing a physical link of the expander from transmitting the OPEN_REJECT (RETRY) to another device along the signaling pathway.
4 . The system of claim 1 , wherein:
the controller is further operable to retransmit the OPEN Address Frame a number of times based on an Arbitration Wait Time of the OPEN Address Frame.
5 . The system of claim 1 , wherein:
the controller is further operable to review the OPEN Address Frame to identify an end device that sourced the OPEN Address Frame, and to retransmit the OPEN Address Frame a number of times based on a number of expanders located between the coupled device and the end device that sourced the OPEN Address Frame.
6 . The system of claim 1 , wherein the expander comprises:
multiple physical links, including the physical link; and
an Expander Connection Router operable to establish electrical connections between the multiple physical links; and
the controller comprises an Expander Connection Manager.
7 . The system of claim 1 , wherein:
the controller comprises:
link layer circuitry for the physical link, operable to receive the OPEN_REJECT (RETRY) from the coupled device; and
link layer circuitry for a second physical link, operable to block transmission of the OPEN_REJECT (RETRY) outside of the expander, and to resend the OPEN Address Frame to the physical link.
8 . A method comprising:
transmitting an OPEN Address Frame to a coupled Serial Attached Small Computer System Interface device, via a physical link of a Serial Attached Small Computer System Interface expander;
receiving, at the physical link, an OPEN_REJECT (RETRY) from the coupled device in response to the OPEN Address Frame;
blocking transmission of the OPEN_REJECT (RETRY) out of the expander in order to preserve a signaling pathway established for the OPEN Address Frame; and
retransmitting the OPEN Address Frame to the coupled device via the physical link.
9 . The method of claim 8 , wherein:
the coupled device comprises an end device, and the method further comprises:
blocking transmission of the OPEN_REJECT (RETRY) in response to determining that the physical link is directly attached to the end device.
10 . The method of claim 8 , wherein:
blocking transmission of the OPEN_REJECT (RETRY) comprises preventing a physical link of the expander from transmitting the OPEN_REJECT (RETRY) to another device along the signaling pathway.
11 . The method of claim 8 , further comprising:
retransmitting the OPEN Address Frame a number of times based on an Arbitration Wait Time of the OPEN Address Frame.
12 . The method of claim 8 , further comprising:
reviewing the OPEN Address Frame to identify an end device that sourced the OPEN Address Frame; and
retransmitting the OPEN Address Frame a number of times based on a number of expanders located between the coupled device and the end device that sourced the OPEN Address Frame.
13 . The method of claim 8 , wherein the expander comprises:
multiple physical links, including the physical link, and the method further comprises
operating an Expander Connection Router, based on input from an Expander Connection Manager, to establish electrical connections between the multiple physical links.
14 . The method of claim 8 , further comprising:
receiving the OPEN_REJECT (RETRY) from the coupled device, via link layer circuitry for the physical link; and
blocking transmission of the OPEN_REJECT (RETRY) outside of the expander, and resending the OPEN Address Frame to the physical link, via link layer circuitry for a second physical link.
15 . A system comprising:
a Serial Attached Small Computer System Interface expander, comprising:
a means for transmitting an OPEN Address Frame to a coupled Serial Attached Small Computer System Interface device, and for receiving an OPEN_REJECT (RETRY) from the coupled device in response to the OPEN Address Frame; and
a means for blocking transmission of the OPEN_REJECT (RETRY) out of the expander in order to preserve a signaling pathway established for the OPEN Address Frame, and retransmitting the OPEN Address Frame to the coupled device via the physical link.
16 . The system of claim 15 , wherein:
the coupled device comprises an end device, and
the means for blocking is further for blocking transmission of the OPEN_REJECT (RETRY) in response to determining that the physical link is directly attached to the end device.
17 . The system of claim 15 , wherein:
blocking transmission of the OPEN_REJECT (RETRY) comprises preventing a physical link of the expander from transmitting the OPEN_REJECT (RETRY) to another device along the signaling pathway.
18 . The system of claim 15 , wherein:
the means for blocking is further for retransmitting the OPEN Address Frame a number of times based on an Arbitration Wait Time of the OPEN Address Frame.
19 . The system of claim 15 , wherein:
the means for blocking is further for reviewing the OPEN Address Frame to identify an end device that sourced the OPEN Address Frame, and for retransmitting the OPEN Address Frame a number of times based on a number of expanders located between the coupled device and the end device that sourced the OPEN Address Frame.
20 . The system of claim 15 , wherein:
the means for transmitting comprises one of multiple physical links of the expander;
the means for blocking comprises an Expander Connection Manager of the expander; and
the expander further comprises an Expander Connection Router operable to establish electrical connections between the multiple physical links.