SAS under/over flow

Eddy Quicksall Quicksall_iSCSI at bellsouth.net
Wed Sep 12 07:51:33 PDT 2007


* From the T10 Reflector (t10 at t10.org), posted by:
* "Eddy Quicksall" <Quicksall_iSCSI at bellsouth.net>
*
I'm sorry I don't know much about SAS yet so I may ask some questions that 
have obvious answers in the spec but which I am not able to find easily.
Anyway,
1) if the target does not have the number of expected transfer bytes, then 
the initiator must be able to limit the amount of data flowing from the line 
into its buffers, is that correct? If so, how since it is not interlocked 
like pSCSI is.
2) can the initiator determine how many bytes were received? If so it can 
set the U and O bits for its O/S requirements.
Eddy
----- Original Message ----- 
From: <Gary.Franco at Emulex.Com>
To: <Quicksall_iSCSI at bellsouth.net>; <t10 at t10.org>
Sent: Tuesday, September 11, 2007 6:29 PM
Subject: RE: SAS under/over flow
Eddy,
You don't see it because it is not there!
This has been a bone of contention with me since day one, but I guess
they did not want to "take" too much from fibre channel.
To me this is a shortcoming, and there is no way for the sas device to
report an underflow/overflow in a check condition mainly because the SSP
frame does not carry the data length for the i/o (like in fibre
channel). If the SSP target does not know how much is being requested
for a read or write, it is pretty hard to report these conditions
without it.
Sometimes, these are not necessarily catastrophic failings.
Ok, time to fold up my soapbox and head to the watering hole!
-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Eddy
Quicksall
Sent: Tuesday, September 11, 2007 4:35 PM
To: t10 at t10.org
Subject: SAS under/over flow
* From the T10 Reflector (t10 at t10.org), posted by:
* "Eddy Quicksall" <Quicksall_iSCSI at bellsouth.net>
*
How does the initiator determine underflow or overflow? I don't see it
in the response frame.
*
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