From owner-freebsd-scsi@FreeBSD.ORG Sun Sep 21 08:42:28 2014 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id ACC02A58 for ; Sun, 21 Sep 2014 08:42:28 +0000 (UTC) Received: from anubis.delphij.net (anubis.delphij.net [64.62.153.212]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "anubis.delphij.net", Issuer "StartCom Class 1 Primary Intermediate Server CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 92813DAB for ; Sun, 21 Sep 2014 08:42:28 +0000 (UTC) Received: from delphij-macbook.local (unknown [106.120.42.90]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by anubis.delphij.net (Postfix) with ESMTPSA id 6ABF319C05; Sun, 21 Sep 2014 01:42:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=delphij.net; s=anubis; t=1411288948; x=1411303348; bh=NcV5Nx5P2IOcDlpzA1WUIAdVpmO02vnVWtybK8HNrYE=; h=Date:From:Reply-To:To:Subject:References:In-Reply-To; b=cSEgFl72LBwSF+ffZVIzGevrwc4X5DMjEXU0fgDEfA/T86xSD3sOa8D2eXoXeEefX hZ+HCNqgk02HVatLp5YLeATEYZZHlVoZcWyTTzpTSaaun2xTYFJZcqlnJ60v7mdE1F 9V/yx5RdREyIrnDAcEDSNEVgsEgE4ys7loA4ckoA= Message-ID: <541E8F72.4020202@delphij.net> Date: Sun, 21 Sep 2014 16:42:26 +0800 From: Xin Li Reply-To: d@delphij.net Organization: The FreeBSD Project MIME-Version: 1.0 To: Matthias Andree , freebsd-scsi@freebsd.org Subject: Re: How to disable hard disk write cache? References: <541804B0.7070407@gmail.com> <54184484.1070304@delphij.net> <541E8DAE.8010407@gmx.de> In-Reply-To: <541E8DAE.8010407@gmx.de> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 21 Sep 2014 08:42:28 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 9/21/14 4:34 PM, Matthias Andree wrote: > Am 16.09.2014 um 16:09 schrieb Xin Li: > >> Modern SATA/SAS/SCSI devices usually comes with the capability >> of tagged commands, allowing the OS to know when a write buffer >> is on stable storage. With this, file systems can easily >> implement the right semantics and recover from e.g. a power >> outage, etc. > > Yes, they *can easily implement* that, but which file systems in > FreeBSD *actually do* that? Both UFS (with Soft Updates, which is what it's all about; I haven't checked the Journalled Soft Updates case) and ZFS do that for ages. Cheers, -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJUHo9xAAoJEJW2GBstM+nsMo0P/2oyyJeH0LOvGGMIDJWw4CZf WGbEcecdQ3idVAw/2j/aYrlGpeYpGNZWi7dv5MOc3jdWRQbGkZ5r3E90YaSiwLac CRix+ovXeM+g7KSfb4q5NNrn9SEpQe8AklS5deTiFP3JxfV4juAf/aXUoCtrpdhm acVh0jYpel5ffdKDzXrHpKItvZ7t0YBg2qATK83+TGJ5cdefcEQnvKnOBMShyM4U ReOoeFO1y8ZBh9aVSYJlMarghxVXar212MavvLJxvKruQE++xf2lnhf8BkvCRiSd Xz24LZMJ/Cz92jMuYbCQ7sX4iIDkcCzpZeVOO8NjBE4YCc5XOCeIvw4uUdLwuWEz QqLLZYbepN1cjPraSrmNH8wFA6kZIQuZvMb3JJt6zRR8621VDg2IABAA4KyKs9CB 74shN5alKNCiDNf75EXfcZL30lTx8KDf/dPAil/mtYc0s7Orwc6veRDVmshCvSH+ y+f5NMYyOuVVoSrGNIhdP21c7vRyAywUVKgBT7IbnZg8I5ORNumCNcSFt+Q8c9Az sIC2cR2XVqCRQpH7qnfoot1e0FwUJEdyOHupVVMlTzFb55z06k79/w1/rruY4ylT rSunaKPy5xm4e43JxgzNhXobH6Qd0qO9VxB5nNb4By52GDccS5xIQw6v36TVXorn WfdQb0tZYKfnlE8tjCKH =MkPK -----END PGP SIGNATURE-----