REC ELS parameter field

Kevin D Butt kdbutt at us.ibm.com
Tue Mar 17 09:11:00 PDT 2009


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r0903174_f.htm">HTML-formatted message</a>

Kevin,
The FCP-4 working group is looking to find if the use of the parameter 
field (Frame Header parameter) is used in a consistent enough manner in 
the LS_ACC to a REC ELS to state in FCP-4 what it should be set to.  My 
response was to state what IBM tape drives put in this field.
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/ 
From:
"Kevin Jones" <kev at bri.hp.com>
To:
Kevin D Butt/Tucson/IBM at IBMUS, t10 at t10.org
Cc:
bob.nixon at emulex.com
Date:
03/17/2009 08:25 AM
Subject:
Re: REC ELS parameter field
I'm confused.
Are we talking about to REC.LS_ACC.Word5 (Frame header parameter)
or REC.LS_ACC.Word10 (Frame Payload FC4VALUE) see FCP4 section 6.5 ?
HP LTO drives set REC.LS_ACC.Word5 = 0.
HP LTO drives set REC.LS_ACC.Word10 = bytes read/written.
Kevin Jones
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On Tue, 17 Mar 2009 14:23:52 -0000, Kevin D Butt <kdbutt at us.ibm.com> 
wrote:
> In response to the question sent on the reflector:
>
> FCP-4 folks: FC-LS requires that ?The value of the Parameter field in 
the
> Frame_Header of an REC ELS and an LS_ACC in response to an REC ELS shall
> be specified by the FC-4 that sends the frame.? FCP-4 specifies the 
value
> of the Parameter field for the ELS but not for the LS_ACC.
>What do people actually do for the LS_ACC? Is it consistent enough to say
> something in FCP-4?
>
>
> The parameter field of LS_ACC is the same as the parameter field of REC
> ELS, unless an error occurs internal to the tape drive which requires 
the
> entire command to be redriven.  In that case, the parameter field of the
> LS_ACC is set to zero to indicate an FCP_RO of zero.	The intent is for
> the initiator port to discard any previously received data and redrive 
the
> command by sending an SRR with a relative offset of zero.
>
> 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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