Re: iSCSI : Initiators expected to fake CHECK CONDITIONS.

[Santosh Rao <santoshr@cup.hp.com>]

Julian,

I had 2 concerns on the format error handling issue :

1) This error recovery is applicable for the SCSI Command PDU. What is the
error recovery for a format error on a Login, Logout, Text, NOP-OUT, NOP-IN,
SCSI Task Management Command PDU ? These commands are either :
not from the scsi layer and their responses do not get sent up the stack to
the scsi layer.
or
in the case of scsi task mgmt cmds, the response does not contain sense data.

How are the above to be handled ?

2) On the concept of initiators generating sense data on behalf of targets and
faking a HARDWARE ERROR, this is not the approach parallel scsi and fibre
channel take. In the case of fibre channel, a header format error results in
Response Info being generated in FCP_RSP. (for scsi pdu's). However, I noticed
that the latest version of the iSCSI draft has removed all references to
response length and response data, and hence, it looks like this approach is
not being considered (?)

Generating sense data in an initiator is adding complexity and makes iSCSI HBA
drivers SPC-2 aware in terms of the content and generation of sense data.
Also, we will need to check some implementations of the upper scsi layer
drivers to see if this can cause any different form of error recovery to be
taken such as issuing a BDR to recover from HARDWARE ERRORs ?

Regards,
Santosh


> Subject:  Re: iSCSI : Initiators expected to fake CHECK CONDITIONS.
> Date:    Fri, 12 Jan 2001 09:41:36 +0200
> From:  julian_satran@il.ibm.com
> To:      ips@ece.cmu.edu

> Santosh,

> A machine producing a format error is DEFECTIVE and this a reported as
> hardware error by SCSI (as SCSI does not distinguish between hardware and
> firmware and rightfully so).


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