Bi-Directional Commands.

Santosh Rao santoshr at
Tue Jan 16 15:48:59 PST 2001

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* Santosh Rao <santoshr at>
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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

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