SSC-4: Programmable Early Warning question

Tim Jones tjmac at tolisgroup.com
Thu Oct 1 16:12:44 PDT 2009


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r0910013_f.htm">HTML-formatted message</a>

As a software developer, I tend to agree Curtis' comment and would  
add that a PEWS zone defined larger than some mutually agreed upon  
percentage of the total, uncompressed capacity of a given tape (since  
most technologies support more than a single tape capacity for	
writes) be the deciding factor for the "too large" of a value being  
supplied.
Tim
On Oct 1, 2009, at 3:21 PM, 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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