Bi-Directional Commands.

George_Penokie at George_Penokie at
Wed Jan 17 13:52:15 PST 2001

* From the T10 Reflector (t10 at, posted by:
* George_Penokie at
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A bidi command is no different from any other type of SCSI command and as
such only has one status and one set of sense data if an error occurs
during the processing of that command by the target.

Bye for now,
George Penokie

Dept 2C6  114-2 N212
E-Mail:    gpenokie at
Internal:  553-5208
External: 507-253-5208   FAX: 507-253-2880

Santosh Rao <santoshr at> on 01/16/2001 05:48:59 PM

Sent by:  owner-t10 at

To:   T10 Reflector <t10 at>
Subject:  Bi-Directional Commands.


I have a question regarding the new BI-DI commands and its related
changes that were proposed to SAM-2, SBC-2 (XDWRITEREAD), and the SPI-4,
FCP-3 and iSCSI SCSI Transport protocols.

Was the BI-DI type of operation only intended to be used in a XOR type
I/O (ex: XDWRITEREAD) like a READ-WRITE or WRITE-READ of the same (LBA,
count) ? i.e. Is there an inherent assumption that BI-DI operations will
always result in a single SCSI Status and SCSI Sense for the entire
operation, as opposed to potential individual SCSI Status or Sense for
either the inbound or outbound operation.

Is there a possibility that different SCSI Status or Sense may need to
be returned for the outbound or the inbound portion of the BI-DI
operation rather than the current single status/sense model used in
Response IUs/PDUs ?

Are there any indications that a returned Status or Sense refer to the
outbound or the inbound portion of the exchange ?

Santosh Rao

(See attached file: santoshr.vcf)

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