REC ELS parameter field

Kevin Jones kevin.jones at hp.com
Tue Mar 24 00:43:32 PDT 2009


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r0903240_f.htm">HTML-formatted message</a>

Kevin,
Thanks for the clarification. Everyone is doing the same thing. Which is
good.
Regards
Kevin Jones
===========================================================================
Hewlett-Packard Limited registered Office:
Cain Road, Bracknell, Berks RG12 1HN
Registered No: 690597 England
The contents of this message and any attachments to it are confidential
and may be legally privileged. If you have received this message in error,
you should delete it  from your system immediately and advise the sender.
To any recipient of this message within HP, unless otherwise
stated you should consider this message and attachments as
"HP CONFIDENTIAL".
  ----- Original Message ----- 
  From: Kevin D Butt 
  To: Jones, Kevin Lloyd 
  Cc: bob.nixon at emulex.com ; Dale.Lafollette at sun.com ; Kevin Jones ;
t10 at t10.org 
  Sent: Monday, March 23, 2009 7:37 PM
  Subject: Re: REC ELS parameter field
  Kevin, 
  Sorry, we did confuse two fields. 
  The parameter field of the header is always set to zero. 
  The data transfer count field (used for FCP_RO) is set with bytes
read/written unless an error occurs internal to the tape drive which requires
the entire command to be redriven.  In that case, the data transfer count
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/ 
	From:  "Kevin Jones" <kevin.jones at hp.com>  
	To:  Kevin D Butt/Tucson/IBM at IBMUS, "Kevin Jones" <kev at bri.hp.com>  
	Cc:  bob.nixon at emulex.com, t10 at t10.org, Dale.Lafollette at sun.com  
	Date:  03/19/2009 12:30 AM  
	Subject:  Re: REC ELS parameter field 
-----------------------------------------------------------------------------
-
  Kevin,
  I am still somewhat confused.
  The frame header parameter field of a REC ELS request is usually
  set to the task retry identifier (assuming TRID is enabled).
  You stated:
  > The parameter field of LS_ACC is the same as theparameter field of REC
unless
  which suggests you set the REC response frame header parameter
  field to TRID ?
  > 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
  which suggests that in the event of an error, the parameter field
  switches from being a TRID to being a "data transferred" indicator,
  which would be a duplication of REC.LS_ACC.Word10 (FC4VALUE) ?
  Regards
  Kevin Jones
  ===========================================================================
  Hewlett-Packard Limited registered Office:
  Cain Road, Bracknell, Berks RG12 1HN
  Registered No: 690597 England
  The contents of this message and any attachments to it are confidential
  and may be legally privileged. If you have received this message in error,
  you should delete it	from your system immediately and advise the sender.
  To any recipient of this message within HP, unless otherwise
  stated you should consider this message and attachments as
  "HP CONFIDENTIAL".
  On Tue, 17 Mar 2009 16:11:00 -0000, Kevin D Butt <kdbutt at us.ibm.com> wrote:
  > 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
  >
  >
===========================================================================
  > Hewlett-Packard Limited registered Office:
  > Cain Road, Bracknell, Berks RG12 1HN
  > Registered No: 690597 England
  >
  > The contents of this message and any attachments to it are confidential
  > and may be legally privileged. If you have received this message in
error,
  > you should delete it  from your system immediately and advise the sender.
  >
  > To any recipient of this message within HP, unless otherwise
  > stated you should consider this message and attachments as
  > "HP CONFIDENTIAL".
  >
  >
  >
  > 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/



More information about the T10 mailing list