Aaah! You are asking the question
I was trying to highlight in my editors note. By adding "on
the BOP side" I have changed the behavior in the case you are asking
about. Prior to my change, if the PEWZ were small enough that a single
write crossed into PEWZ and out into EW, then there would be no PEW CC
but only the EW CC. My proposed change would change this to require
both CC's. I think this is what was intended when I originally made
the proposal to add PEWZ. However, there was quite the discussion
in the working group, especially by the ISV present, and I don't want to
take anything for granted.
Given this change and looking at it
again, I think I have under-specified the behavior. I need to add
that the PROGRAMMABLE EARLY
WARNING DETECTED CHECK CONDITION shall
occur before the EW CC.
I am positive this will illicit a debate
in the next SSC-3 WG meeting. This is why I asked for careful scrutiny.
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/
| From:
| "Knight, Frederick" <Frederick.Knight@netapp.com>
|
| To:
| Kevin D Butt/Tucson/IBM@IBMUS
|
| Date:
| 09/29/2008 10:00 AM
|
| Subject:
| RE: SSC-3: Resolution to LB HPQ-70 |
I guess I wasn't clear. For
this case of transitioning out of PEWZ:
If you transition into PEWZ, and
then transition out of PEWZ into EW, what do you get?
For example, the host mistakenly
configures a PEWZ that is too small (so a large write
crosses into both zones). Do
you get:
BOTH check conditions (queued),
or just the EW check condition (the PEWZ one is replaced)?
I assume based on the text I quoted,
you get just the EW check condition; it is reported "instead".
Fred
From: Kevin D Butt [mailto:kdbutt@us.ibm.com]
Sent: Monday, September 29, 2008 12:44 PM
To: Knight, Frederick
Subject: RE: SSC-3: Resolution to LB HPQ-70
Fred,
The Programmable Early Warning sets up an additional check condition prior
to the Early Warning (EW) Check Condition. So, IF an application
client sets up PEWS in the mode page, then when the tape position crosses
into PEWZ (i.e., location of EW - PEWS) then the new check condition is
returned. Then, presumably at a later time, when the tape position
crosses into EW, the existing EW check condition will be returned. So,
the is a new CC prior to EW that is returned if and only if the mode page
is set up to have this programmable early warning zone and there is the
normal check condition(s) for EW. As I recall, the application client
will get a CC on every write after EW, but this might be configurable.
I can't find where you would configure it, but I know that some devices
will report CC on each and every write after EW.
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/
| From:
| "Knight, Frederick"
<Frederick.Knight@netapp.com>
|
| To:
| Kevin D Butt/Tucson/IBM@IBMUS
|
| Date:
| 09/29/2008 05:27 AM
|
| Subject:
| RE: SSC-3: Resolution to LB HPQ-70 |
Isn't there another CC that occurs when entering EW? Am I remembering
right (I didn't check)?
Should there now be 2 CCs if you make it through PEWZ and into EW prior
to the first PEWZ CC being delivered? or should the second one (entering
EW) replace the PEWZ one? It seems that you've covered this case
by saying that if another condition occurs, then that condition shall be
reported instead.
If processing this command results in
any
other exception condition, the CHECK CONDITION
status associated with that exception condition shall be
reported instead.
I have no issue with the changes
you've proposed here.
Fred
From: Kevin D Butt [mailto:kdbutt@us.ibm.com]
Sent: Wednesday, September 24, 2008 5:02 PM
To: t10@t10.org
Subject: SSC-3: Resolution to LB HPQ-70
I have posted a proposal (http://www.t10.org/ftp/t10/document.08/08-389r0.pdf)
to resolve SSC-3 Letter Ballot comment LB HPQ-70 related to the programmable
early warning indication that was added as part of the solicited ISV requests.
Tim, Roger, and Ray,
Please pay attention to the functional change this proposal makes. It
bears on when the CC will and will not be returned. I thought the
description was intended to be entering PEWZ and exiting on BOP side prior
to the indication being given. As written it also includes entering
PEWZ and exiting into EW prior to CC being given. I don't think that
was our intent, but please check to make sure.
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/