RE: iSCSI: DataACK SNACK

["Julian Satran" <Julian_Satran@il.ibm.com>]

I agree but let's hear arguments against if they are any. Julo

Eddy Quicksall <Eddy_Quicksall@ivivity.com> 16-02-02 19:47

To:        Julian Satran/Haifa/IBM@IBMIL, Chuck Micalizzi <chuck.micalizzi@qlogic.com>, cbm@rose.hp.com         cc:        ips@ece.cmu.edu         Subject:        RE: iSCSI: DataACK SNACK

Because of what Chuck pointed out, my feeling is that the TTT should be provided when the A bit is set. It also makes the association faster since the ITT would require a search by the target.

 

Eddy

 

-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Saturday, February 16, 2002 2:52 AM
To: Chuck Micalizzi
Cc: ips@ece.cmu.edu
Subject: RE: iSCSI: DataACK SNACK

 

Chuck,

The Initiator Task Tag is thhe only reliable indicator the protocol provides today.
If nobody shouts against it we might let the target provide a Target Transfer Task for Data-In PDUs that have the A bit set
to be returned with the ACK for target convenience.

Julo

"Chuck Micalizzi" <chuck.micalizzi@qlogic.com> 15-02-02 23:14

To:        Julian Satran/Haifa/IBM@IBMIL        cc:        <ips@ece.cmu.edu>        Subject:        RE: iSCSI: DataACK SNACK

Julian,
 
   Thank you for the response.
 
   Let me try to be  more direct. If a target has been issued multiple
   read commands, with transfer counts that exceed the negotiated
   maxBurstSize. After the target sends a data sequence for one of these
   commands must it wait for a DataACK before sending a data sequence
   for another command. Or is it free to send a data sequence for each outstanding
   command?
 
   If the target can have a data sequence in flight for each active command then
   it must expect a DataACK for each sequence sent with the Acknowledge
   bit set. If the DataACK SNACK doesn't include a task Tag the target can't be
   certain as to which data sequence the initiator is acknowledging.  So how can
   the target determine which resources to free or which sequence to send next?
 
chuck
 
   
 
   
 
   
-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Friday, February 15, 2002 9:30 AM
To: Chuck Micalizzi
Cc: ips@ece.cmu.edu; owner-ips@ece.cmu.edu
Subject: Re: iSCSI: DataACK SNACK


DataACK is a "bulk ack". Answering the last (in case of several) is good enough.
I fail to see your point.

Julo

"Chuck Micalizzi" <chuck.micalizzi@qlogic.com> Sent by: owner-ips@ece.cmu.edu 14-02-02 21:02

To:        <ips@ece.cmu.edu>       cc:               Subject:        iSCSI: DataACK SNACK

All,
 
 I have a question regarding DataACK.

 Rev. 10 section 10.16.1 states:

 For a Data/R2T SNACK, the Initiator Task Tag MUST be set
 to the Initiator Task Tag of the referenced Command.
 Otherwise, it is reserved.

 it also states:

 The DataACK is used to free resources at the target and
 not to request or imply data retransmission.

 Is the target allowed to have more than one DataACK
 outstanding on a connection?    

 If multiple outstanding DataACKs are allowed per connection
 then in my opinion the DataACK must have a valid task tag
 inorder for the target to associate the DataACK with the
 appropriate resources to be freed.


chuck micalizzi
Qlogic Corp.