Subject: RE: Relative offset calculation with data protection enabled Date: Tue, 6 Jun 2006 13:16:39 -0500 From: "Elliott, Robert (Server Storage)" <Elliott@hp.com> To: <t10@t10.org> X-Message-Number: 6931 Formatted message: HTML-formatted message Attachment #1: smime.p7s Protection information is a SCSI Block command set concept. The Fibre Channel and FCP layers just transfer bytes for the SCSI layer. They don't know if the command they are carrying is block-based or not, what the block size is, or even what a "block" is. Some SCSI command sets like OSD (object storage) and SSC (tapes) have totally different concepts of the granularity of media accesses than SBC (disks). So, the Parameter field in the FCP frame header, which serves as a Relative Offset field for FCP_DATA IUs, is based on the number of bytes actually transferred (e.g., 520 bytes per block) not the amount of user data (e.g., 512 bytes per block). -- Rob Elliott, elliott@hp.com Hewlett-Packard Industry Standard Server Storage Advanced Technology https://ecardfile.com/id/RobElliott _____ From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Gary.Franco@emulex.com Sent: Tuesday, June 06, 2006 11:24 AM To: t10@t10.org Subject: Relative offset calculation with data protection enabled All, I have been trying to find some statement in the various documents defining data protection, SPC/SBC and have yet to find anything discussing relative offset generation with a data protection enabled device or initiator. Is the relative offset field still generated on 512 byte blocks and the DIF field just an opaque object that we have to deal with? When a check and translate function is requested (DIF embedded in the data-in or data-out buffer) does the above still hold true? If you know where I can find this information I would appreciate a reply. __________________________________ Gary Franco Consultant Engineer Emulex Network Systems 972-671-7433 Dallas Office 972-671-7435 Dallas Office Fax 720-652-6387 Longmont Colorado Office 720-494-1817 Longmont Colorado Office Fax 972-839-5694 Cell Phone Today's Quote It is not the cards you are dealt but what you do with them that counts. -Anonymous This message contains confidential information of Emulex Corporation intended only for listed recipients and should not be forwarded to anyone else. If you have received this message in error, please delete it immediately. Thank you.