Re: iSCSI : Bridging missing CmdSNs and Abort I/O Error recovery

[julian_satran@il.ibm.com]

I the hole is in the command queue and the task is just aborted the
response to the abort task
will unveil the fact that it did not reach destination.

Initiator can recover from there in several ways - clear the task set, fill
the hole with an iSCSI noop etc.
The latter, I recall, Was sugested to you by Matt Wakeley a while ago.

None of them require any changes in the spec.

Julo


Santosh Rao <santoshr@cup.hp.com> on 27/04/2001 04:56:26

Please respond to Santosh Rao <santoshr@cup.hp.com>

To:   Julian Satran/Haifa/IBM@IBMIL
cc:   ips@ece.cmu.edu
Subject:  Re: iSCSI : Bridging missing CmdSNs and Abort I/O Error recovery




Julian,

Could you please clarify if the below issue is going to be addressed in
the iSCSI draft, as was discussed earlier.
(http://ips.pdl.cs.cmu.edu/mail/msg03155.html).

Specifically, is the spec going to address the issue of how initiators
can plug a hole in CmdSN sequence when they detect a ULP timeout and/or
choose not to use "command retry".

Regards,
Santosh

julian_satran@il.ibm.com wrote:
>
> Santosh,
>
> You had a possible answer from Matt.  However I agree that we might want
to
> address this in text although
> a solution similar to that suggested by Matt should be by now obvious to
> every implementer - the target should leave a placeholder in the input
> queue until the command after gets delivered.
>
> Julo
>
> Santosh Rao <santoshr@cup.hp.com> on 25/01/2001 21:38:04
>
> Please respond to Santosh Rao <santoshr@cup.hp.com>
>
> To:   IPS Reflector <ips@ece.cmu.edu>
> cc:
> Subject:  iSCSI : Bridging missing CmdSNs and Abort I/O Error recovery
>
> Julian & All,
>
> The draft is currently lacking a section that addresses abort I/O error
> recovery. Specifically, how is CmdSN bridging issues to be handled in
> the case where an initiator chooses not to retry an I/O [that failed on
> a connection failure that affects the delivery of the command to the
> target or a digest error at the target] because its ULP timer may have
> expired.
>
> In such cases, the initiator can send an Abort Task to inform the target
> that the I.T.T is being aborted and its corresponding CmdSN can be
> bridged, instead of having the target stall infinitely in its attempt to
> enforce ordering and await the missing CmdSN [which is'nt going to
> arrive, because the initiator did not retry the command].
>
> Regards,
> Santosh
>
>  - santoshr.vcf
 - santoshr.vcf