From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: [PATCH 1/4] target/core: T10-Dif: check HW support capabilities Date: Tue, 01 Apr 2014 13:09:37 -0400 Message-ID: References: <1396047927-14189-1-git-send-email-quinn.tran@qlogic.com> <1396047927-14189-2-git-send-email-quinn.tran@qlogic.com> <53360E54.5060004@mellanox.com> <504EB66DAC8D234EB8E8560985C2D7AD46CE87D7@avmb2.qlogic.org> <533620C0.9060903@mellanox.com> <504EB66DAC8D234EB8E8560985C2D7AD46CE9B32@avmb2.qlogic.org> <1396315146.22665.82.camel@haakon3.risingtidesystems.com> <533A71E9.90308@dev.mellanox.co.il> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from userp1040.oracle.com ([156.151.31.81]:30492 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751316AbaDARJw (ORCPT ); Tue, 1 Apr 2014 13:09:52 -0400 In-Reply-To: <533A71E9.90308@dev.mellanox.co.il> (Sagi Grimberg's message of "Tue, 01 Apr 2014 10:59:37 +0300") Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Sagi Grimberg Cc: "Nicholas A. Bellinger" , Quinn Tran , sagi grimberg , "target-devel@vger.kernel.org" , linux-scsi , Giridhar Malavali , Saurav Kashyap , Andrew Vasquez >>>>> "Sagi" == Sagi Grimberg writes: Sagi> I originally wrote the code to support that. But it got left Sagi> behind since I figured it is not an interesting use-case. If your Sagi> beckend doesn't support T10-PI why should the target publish it Sagi> support it and ask the device to strip/insert it? I suppose it is Sagi> to allow the initiator to protect half-way, but I don't know how Sagi> interesting it is if the data is not stored with protection... That depends what you do on the backend. There are several devices out there that expose PI to the host but use a different protection scheme internally. And then synthesize PI on the host-facing side. Some even do T10 PI to an internal protection scheme and then back to T10 PI when talking to the disk drives in the back end. -- Martin K. Petersen Oracle Linux Engineering