Wide Links and Wide Ports

David Freeman david.freeman at datatransit.com
Mon Feb 24 15:42:10 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "David Freeman" <david.freeman at datatransit.com>
*
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I seem to be confused about how wide ports and wide links are handled.
Section 8.3.3.1.4 of the SAS spec. (rev. D) says...
=20
"  A wide port shall only transmit DATA frames for a given I_T_L_Q =
nexus
on one phy at a time. The wide port may switch phys for DATA frames =
once
all of the previous DATA frames have been acknowledged by the link
layer. Read DATA frames and write DATA frames for the same I_T_L_Q =
nexus
may be transmitted simultaneously and may be on the same or different
phys."
=20
Does this mean that inside a wide link all of the frames between and
including the "Command" frame and the "Response" frame will only occur
on one physical link?
=20
This seems to defeat the purpose of having a wide link.
=20
If there is any one out there that could help clear this confusion, I
would appreciate it.
=20
Thank You=20
=20
David R. Freeman
Data Transit

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I seem to be confused about how wide = ports and wide=20 links are handled. Section 8.3.3.1.4 of the SAS spec. (rev. D)=20 says...
  
 "  A = wide port shall=20 only transmit DATA frames for a given I_T_L_Q nexus on one phy at a = time. The=20 wide port may switch phys for DATA frames once all of the previous DATA = frames=20 have been acknowledged by the link layer. Read DATA frames and write = DATA frames=20 for the same I_T_L_Q nexus may be transmitted simultaneously and may be = on the=20 same or different phys."
  
 Does this mean that inside a wide = link all of=20 the frames between and including the "Command" frame and the "Response" = frame=20 will only occur on one physical link?
  
 This seems to defeat the purpose of = having a wide=20 link.
  
 If there is any one out there that = could help clear=20 this confusion, I would appreciate it.
  
 Thank You 
 
 David R. Freeman
 Data = Transit


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