RE: iSCSI: underrun with a check condition

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

Eddy,

If a device has a UA condition it will
answer with either BUSY or ACA Active to the read (not check condition).
All other fields of the iSCSI response
are irrelevant in this case - SCSI is silent on this but based on just
common sense I would guess you don't want to set U as it may imply that
the target has estimated the size of the underrun based on Length, device
and CDB information.

Julo

Eddy Quicksall <eddyq@ivivity.com>

16/02/03 14:34

To	Julian Satran/Haifa/IBM@IBMIL
cc	"Ips@Ece.Cmu.Edu (ips@ece.cmu.edu)" <ips@ece.cmu.edu>, owner-ips@ece.cmu.edu
Subject	RE: iSCSI: underrun with a check condition

I'm sorry; I should have been
more specific. Let's take a very simple case:

 

I->T READ 1 block

T->I Unit Attention (06/29/01)

(or BUSY, etc)

 

Since all of the data was not returned, should the U bit be set? Section 10.4.1 does not specify.

 

     bit 6 - (U) set for Residual Underflow. In this case, the

       Residual Count indicates the number of bytes that were not

       transferred out of the number of bytes that were expected to

       be transferred. For a bidirectional operation, the Residual

       Count contains the residual for the write operation.

 

Eddy

 

-----Original Message-----
From: Julian Satran [mailto:Julian_Satran@il.ibm.com]
Sent: Sunday, February 16, 2003 2:32 AM
To: Eddy Quicksall
Cc: Ips@Ece.Cmu.Edu (ips@ece.cmu.edu); owner-ips@ece.cmu.edu
Subject: Re: iSCSI: underrun with a check condition

 

For some devices and settings the underrun may the cause of the check condition so it certainly should be set whenever appropriate.


Julo

Eddy Quicksall <eddyq@ivivity.com>
Sent by: owner-ips@ece.cmu.edu

15/02/03 04:57

To	"Ips@Ece.Cmu.Edu (ips@ece.cmu.edu)" <ips@ece.cmu.edu>
cc
Subject	iSCSI: underrun with a check condition

 

Should the target set the U bit when it gives a check condition to a data-in command?

 

 

Eddy

mailto: Eddy_Quicksall@iVivity.com