From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f52.google.com ([74.125.82.52]:61034 "EHLO mail-wg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751142AbaK1PzL (ORCPT ); Fri, 28 Nov 2014 10:55:11 -0500 Received: by mail-wg0-f52.google.com with SMTP id a1so9166885wgh.25 for ; Fri, 28 Nov 2014 07:55:10 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <5474FF63.5030008@ubuntu.com> References: <546AF572.2020101@swiftspirit.co.za> <20141118153526.GS20972@merlins.org> <47FB8035-FEA6-40E1-9672-5BBF92B283A9@colorremedies.com> <546BB2EA.5080809@ubuntu.com> <546CC04F.6040207@ubuntu.com> <5474FF63.5030008@ubuntu.com> Date: Fri, 28 Nov 2014 16:55:10 +0100 Message-ID: Subject: Re: scrub implies failing drive - smartctl blissfully unaware From: Patrik Lundquist To: Phillip Susi Cc: "linux-btrfs@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 25 November 2014 at 23:14, Phillip Susi wrote: > On 11/19/2014 6:59 PM, Duncan wrote: > >> The paper specifically mentioned that it wasn't necessarily the >> more expensive devices that were the best, either, but the ones >> that faired best did tend to have longer device-ready times. The >> conclusion was that a lot of devices are cutting corners on >> device-ready, gambling that in normal use they'll work fine, >> leading to an acceptable return rate, and evidently, the gamble >> pays off most of the time. > > I believe I read the same study and don't recall any such conclusion. > Instead the conclusion was that the badly behaving drives aren't > ordering their internal writes correctly and flushing their metadata > from ram to flash before completing the write request. The problem > was on the power *loss* side, not the power application. I've found: http://www.usenix.org/conference/fast13/technical-sessions/presentation/zheng http://lkcl.net/reports/ssd_analysis.html Are there any more studies?