From owner-freebsd-fs@FreeBSD.ORG Sun Oct 16 20:03:12 2011 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 84F811065676 for ; Sun, 16 Oct 2011 20:03:12 +0000 (UTC) (envelope-from julian@freebsd.org) Received: from vps1.elischer.org (vps1.elischer.org [204.109.63.16]) by mx1.freebsd.org (Postfix) with ESMTP id 560748FC13 for ; Sun, 16 Oct 2011 20:03:12 +0000 (UTC) Received: from julian-mac.elischer.org (home-nat.elischer.org [67.100.89.137]) (authenticated bits=0) by vps1.elischer.org (8.14.4/8.14.4) with ESMTP id p9GK2ri7046326 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Sun, 16 Oct 2011 13:02:58 -0700 (PDT) (envelope-from julian@freebsd.org) Message-ID: <4E9B3876.2010809@freebsd.org> Date: Sun, 16 Oct 2011 13:03:02 -0700 From: Julian Elischer User-Agent: Mozilla/5.0 (Macintosh; U; PPC Mac OS X 10.4; en-US; rv:1.9.2.23) Gecko/20110920 Thunderbird/3.1.15 MIME-Version: 1.0 To: "Luchesar V. ILIEV" References: <4E9AE725.4040001@gmail.com> <169E82FD-3B61-4CAB-B067-D380D69CDED5@digsys.bg> <4E9B1C1E.7090804@gmail.com> <14628DFB-AA3E-4D2D-9D4F-723B6327B6C0@digsys.bg> <4E9B2509.3030701@gmail.com> In-Reply-To: <4E9B2509.3030701@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Cc: freebsd-fs@freebsd.org Subject: Re: [ZFS] Using SSD with partitions X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 16 Oct 2011 20:03:12 -0000 On 10/16/11 11:40 AM, Luchesar V. ILIEV wrote: > > That's true, but my understanding is that the differences go further > beyond that. To quote one paper: "Our data show that flash memory’s > behavior under power failure is surprising in several ways. First, > operations that come closer to completion do not necessarily exhibit > fewer bit errors. Second, power failure not only results in failure of > the operation in progress, it can also corrupt data already present in > the flash device. Third, power failure can negatively impact the > integrity of future data written to the device." However one must not confuse Flash memeory with drives using flash memory. part of the added value brought to the tabel by SSD manufacturers is (SHOULD BE) the addition of mechanisms to cope with unexpected power down. whether it be hold-up caoacitors, battery backed up ram or any other mechanism they can think of. Certainly Fusion-IO Flash cards will never lose data that they have reported as having been written. > http://cseweb.ucsd.edu/users/swanson/papers/DAC2011PowerCut.pdf > > However, that's probably getting too academic (also beyond my own > qualifications), and I wouldn't like to hijack the thread. > > Cheers, > Luchesar > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" > >