Re: iscsi: More immediate data than required data

Barada,

The response depends on where 1024 vs. 2048 bytes are encoded...

If SCSI WRITE(10) TransferLength is set to 2 (512 Blocks) and
iSCSI SCSI Command PDU DataSegmentLength is set to 2048,
then all 2048 bytes SHALL be read by iSCSI Target and only the
first 1024 bytes SHALL be utilized by SCSI Target.

If SCSI WRITE(10) TransferLength is set to 2 (512 Blocks) and
iSCSI SCSI Command PDU DataSegmentLength is set to 1024,
then all 1024 bytes SHALL be read by iSCSI Target and all1024
bytes SHALL be utilized by SCSI Target.

In either case, the iSCSI Target SHALL expect the next iSCSI
PDU to begin immediately after the last...  So if an additional 1024
bytes of unknown data are appended to a PDU, then results are
indeterminate.  The unknown data may be evaluated as another
iSCSI PDU or may be seen as a data corruption on the connection.
If the data is seen as a data corruption, then iSCSI ERROR
RECOVERY LEVEL protocols SHALL be followed.

Cheers,
Joel.

[email protected]
JIST Development Lead
303-272-5556, x75556
"Luck is a Planned Event."

----- Original Message -----
From: Barada Mishra <[email protected]>
Date: Thursday, January 25, 2007 2:10 pm
Subject: [Ips] iscsi: More immediate data than required data
To: [email protected]

> Hi,
> 
> This question is from a iSCSI target point of view.
> 
> When a target receives more immediate data than the required data, 
> whatshould be the behavior?
> 
> Example :
> Assume the target receives a write command for 2 blocks (1024 bytes).
> But the associated immediate data it receives is 2048.
> 
> What should the target do
>  1. Use only 1024 bytes, ignore the rest of data and return good 
> status  2. Return check condition (what should be the ASC/ASCQ)?
>  3. Drop the connection and/or session
>  4. Reject the PDU
> Or something else?
> 
> Thanks
> Barada
>

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