Re: [storm] WG Last Call comments on consolidated iSCSI draft

[Ralph Weber <[e-mail]>]

David, If agreement between the two of us counts as consensus,
then pop open the bubbly. All the best, .Ralph

On 8/30/2011 6:09 PM, [e-mail] wrote:
> I like Ralph's suggestion to include a mention of operating systems in the new test,
> but I have some further tweaks to his words to suggest:
>
> SCSI initiator functionality in some operating systems depends on ACA to enforce
> ordered command execution during error recovery, and hence iSCSI initiator
> implementations for those operating systems need to support ACA.  In order
> to support error recovery for these operating systems and iSCSI initiators,
> iSCSI targets SHOULD support ACA.
>
> Thanks,
> --David
>
>> -----Original Message-----
>> From: [e-mail] [mailto:[e-mail]] On Behalf Of Mallikarjun Chadalapaka
>> Sent: Tuesday, August 30, 2011 1:49 PM
>> To: [e-mail]
>> Subject: Re: [storm] WG Last Call comments on consolidated iSCSI draft
>>
>> I am catching up on this thread after a vacation.
>>
>> I agree in general with the consensus on this thread that we should leave
>> ACA as SHOULD.
>>
>> Specifically, I like David's last rewrite, which succinctly states the
>> rationale in SCSI initiator terms, as appropriate for this spec.  I plan to
>> get that into the next rev.
>>
>> David, thanks for your Last Call review.  I will address your all other
>> comments as well in the next revision.
>>
>> Thanks.
>>
>> Mallikarjun
>>
>>
>>
>>    -----Original Message-----
>>    From: [e-mail] [mailto:[e-mail]] On Behalf
>>    Of Ralph Weber
>>    Sent: Monday, August 29, 2011 12:37 PM
>>    To: [e-mail]
>>    Subject: Re: [storm] WG Last Call comments on consolidated iSCSI draft
>>
>>    A necessary nuance between Operating Systems and initiator products is
>>    missing in the rewrite. How about:
>>
>>    Some operating systems depend on SCSI ACA to enforce ordered command
>>    execution during error recovery, and hence iSCSI initiator implementations
>>    for those operating systems need to support ACA.  In order to support
>> error
>>    recovery for these operating systems and iSCSI initiators, iSCSI targets
>>    SHOULD support ACA.
>>
>>    All the best,
>>
>>    .Ralph
>>
>>    On 8/28/2011 12:27 PM, [e-mail] wrote:
>>    >  I agree - second try at text:
>>    >
>>    >  OLD
>>    >     ACA helps preserve ordered command execution in the presence of
>>    >     errors. As iSCSI can have many commands in-flight between
>>    >     initiator and target, iSCSI initiators and targets SHOULD support
>>    >     ACA.
>>    >  NEW
>>    >     Some SCSI initiators use ACA to enforce ordered command execution
>>    >     during error recovery, and hence iSCSI initiator implementations
>>    >     for those SCSI initiators need to support ACA.  In order to support
>>    >     error recovery for these SCSI and iSCSI initiators, iSCSI targets
>>    >     SHOULD support ACA.
>>    >
>>    >  As Ralph noted, an implementer of an iSCSI initiator that needs ACA
>>    >  will know it, or learn quickly when error recovery doesn't work right
>>    >  wrt the SCSI class driver :-), so the primary purpose of the SHOULD in
>>    >  this text is to tell target implementers about the need for ACA support.
>>    >
>>    >  FWIW, this is a "SHOULD" and not a "MUST" because a target
>>    implementer
>>    >  may choose not to support initiators that use ACA - that absence of
>>    >  ACA support will be detected quickly at the SCSI level, as the first
>>    >  SCSI command that sets the NACA bit in the CONTROL byte in the CDB
>>    >  will get hit with a CHECK CONDITION for having done so.
>>    >
>>    >  Thanks,
>>    >  --David
>>    >
>>    >>  -----Original Message-----
>>    >>  From: [e-mail] [mailto:[e-mail]] On
>>    >>  Behalf Of Julian Satran
>>    >>  Sent: Sunday, August 28, 2011 1:15 AM
>>    >>  To: Ralph Weber
>>    >>  Cc: [e-mail]
>>    >>  Subject: Re: [storm] WG Last Call comments on consolidated iSCSI
>>    >>  draft
>>    >>
>>    >>  Ralph,
>>    >>
>>    >>  I think you caught a nit. Your point is correct - WRT initiators.
>>    >>  The SHOULD statement should refer to targets only.  Initiators that
>>    >>  are not supporting ACA may have a hard time surviving in the same
>>    >>  environment with initiators that require and support ACA  but will
>> cause
>>    no harm to those that require and support it.
>>    >>
>>    >>  Julo
>>    >>  On Aug 28, 2011, at 5:18 AM, Ralph Weber wrote:
>>    >>
>>    >>>  I am having a little bit of difficulty following the logic of the
>>    >>>  proposed new text.
>>    >>>
>>    >>>  First it says that some initiator implementations use ACA (which
>>    >>>  implies that some do not). Then, it says that iSCSI initiators
>>    >>>  (presumably all iSCSI initiators) ... SHOULD support ACA.
>>    >>>
>>    >>>  I can understand why initiators that need ACA SHOULD support it, but
>>    >>>  why should the others bear the burden?
>>    >>>
>>    >>>  All the best,
>>    >>>
>>    >>>  .Ralph
>>    >>>
>>    >>>  On 8/27/2011 5:36 PM, [e-mail] wrote:
>>    >>>>  <WG chair hat off>
>>    >>>>
>>    >>>>  In that case, let's at least get the explanation for the SHOULD right
>> ;-).
>>    >>>>
>>    >>>>  Here's a suggestion ...
>>    >>>>
>>    >>>>  OLD
>>    >>>>     ACA helps preserve ordered command execution in the presence of
>>    >>>>     errors. As iSCSI can have many commands in-flight between
>>    >>>>     initiator and target, iSCSI initiators and targets SHOULD support
>>    >>>>     ACA.
>>    >>>>  NEW
>>    >>>>     Some SCSI initiator implementations use ACA to enforce ordered
>>    >>>>     command execution during recovery from errors.  In order to
>>    support
>>    >>>>     error recovery in such SCSI initiators, iSCSI initiators and
>> targets
>>    >>>>     SHOULD support ACA.
>>    >>>>
>>    >>>>  Thanks,
>>    >>>>  --David
>>    >>>>
>>    >>>>>  -----Original Message-----
>>    >>>>>  From: Knight, Frederick [mailto:[e-mail]]
>>    >>>>>  Sent: Friday, August 26, 2011 8:51 AM
>>    >>>>>  To: Black, David
>>    >>>>>  Cc: [e-mail]
>>    >>>>>  Subject: RE: [storm] WG Last Call comments on consolidated iSCSI
>>    >>>>>  draft
>>    >>>>>
>>    >>>>>  I disagree.
>>    >>>>>
>>    >>>>>  1) while not common, the hosts that use it, do need it;
>>    >>>>>  2) the original 3720 text contains a SHOULD; and
>>    >>>>>  3) there is no good reason for us to be weakening this statement.
>>    >>>>>
>>    >>>>>  	Fred Knight
>>    >>>>>  	NetApp
>>    >>>>>
>>    >>>>>  -----Original Message-----
>>    >>>>>  From: [e-mail] [mailto:[e-mail]]
>>    >>>>>  Sent: Thursday, August 25, 2011 5:55 PM
>>    >>>>>  To: [e-mail]
>>    >>>>>  Subject: [storm] WG Last Call comments on consolidated iSCSI draft
>>    >>>>>
>>    >>>>>  <...text removed...>
>>    >>>>>
>>    >>>>>  [D] Section 10.2 contains a "SHOULD" requirement for ACA
>>    >>>>>  (Auto-Contingent Allegiance) support.
>>    >>>>>  As ACA support in SCSI initiators is not common, I suggest
>>    >>>>>  weakening this to a MAY requirement.
>>    >>>>>
>>    >>>>>
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