SSC-4: Programmable Early Warning question

Dennis Painter dennis at hale-pohaku.net
Thu Oct 1 17:15:52 PDT 2009


* From the T10 Reflector (t10 at t10.org), posted by:
* Dennis Painter <dennis at hale-pohaku.net>
*
Protection from it being set to a value greater that the media capacity 
is good. I favor recovered error as the software can accept it and 
continue or has the option to read the PEWS setting.
Is it allowed for the application client to set PEWS if there is no 
media present? I did not find a restriction in the current draft but it 
may not be where I looked.
If not restricted and media of different capacity is supported then 
there is a potential problem of PEWS being set for a larger capacity 
tape and having a smaller capacity tape inserted. If PEWS is cleared on 
media removal and cannot be set without media present then there would 
be no issue.
Dennis Painter
Ballard, Curtis C (StorageWorks) wrote:
> In the interest of having a complete specification it would be 
> appropriate to specify behavior although I would hope that an 
> application would never make that mistake.
>  
> Rather than reject the command I would be inclined to have a device 
> specific maximum PEWS zone and report a recovered error with the PEWS 
> zone set to the maximum allowed.
>  
> Curtis Ballard
> Hewlett Packard
>
> ------------------------------------------------------------------------
> *From:* owner-t10 at t10.org [mailto:owner-t10 at t10.org] *On Behalf Of 
> *Kevin D Butt
> *Sent:* Thursday, October 01, 2009 1:46 PM
> *To:* t10 at t10.org
> *Subject:* SSC-4: Programmable Early Warning question
>
>
> Tapeheads,
>
> I wonder if we should protect the programmable early warning from 
> being set to too large a value.  Should we add some statement like the 
> following to SSC-4?
>
> If PEWS field of Device Configuration Extension mode page is set to a 
> value larger than the tapes capacity, then the Mode Select should be 
> rejected with ILLEGAL REQUEST, INVALID FIELD IN PARAMETER LIST.
>
> Thanks,
>
> Kevin D. Butt
> SCSI & Fibre Channel Architect, Tape Firmware
> MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
> Tel: 520-799-5280
> Fax: 520-799-2723 (T/L:321)
> Email address: kdbutt at us.ibm.com
> http://www-03.ibm.com/servers/storage/ 
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Protection from it being set to a value greater that the media capacity is
good. I favor recovered error as the software can accept it and continue or
has the option to read the PEWS setting.
Is it allowed for the application client to set PEWS if there is no media
present? I did not find a restriction in the current draft but it may not be
where I looked.
If not restricted and media of different capacity is supported then there is
a potential problem of PEWS being set for a larger capacity tape and having a
smaller capacity tape inserted. If PEWS is cleared on media removal and
cannot be set without media present then there would be no issue.
Dennis Painter
Ballard, Curtis C (StorageWorks) wrote: 
>In the interest of having a complete specification it would be appropriate
to specify behavior although I would hope that an application would never
make that mistake.
> 
>Rather than reject the command I would be inclined to have a device specific
maximum PEWS zone and report a recovered error with the PEWS zone set to the
maximum allowed.
> 
>Curtis Ballard
>Hewlett Packard
>
>
>----------
>From: <mailto:owner-t10 at t10.org>owner-t10 at t10.org [mailto:owner-t10 at t10.org]
On Behalf Of Kevin D Butt
>Sent: Thursday, October 01, 2009 1:46 PM
>To: <mailto:t10 at t10.org>t10 at t10.org
>Subject: SSC-4: Programmable Early Warning question
>
>
>Tapeheads, 
>
>I wonder if we should protect the programmable early warning from being set
to too large a value.  Should we add some statement like the following to
SSC-4? 
>
>If PEWS field of Device Configuration Extension mode page is set to a value
larger than the tapes capacity, then the Mode Select should be rejected with
ILLEGAL REQUEST, INVALID FIELD IN PARAMETER LIST. 
>
>Thanks, 
>
>Kevin D. Butt
>SCSI & Fibre Channel Architect, Tape Firmware
>MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
>Tel: 520-799-5280
>Fax: 520-799-2723 (T/L:321)
>Email address: kdbutt at us.ibm.com
>http://www-03.ibm.com/servers/storage/ 
--------------050506040709020403060503--
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