From owner-freebsd-current@freebsd.org Fri Apr 15 02:01:36 2016 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 56D1FAECFE8 for ; Fri, 15 Apr 2016 02:01:36 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-ig0-x242.google.com (mail-ig0-x242.google.com [IPv6:2607:f8b0:4001:c05::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2A7741787 for ; Fri, 15 Apr 2016 02:01:36 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-ig0-x242.google.com with SMTP id g8so1218666igr.0 for ; Thu, 14 Apr 2016 19:01:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc; bh=GWLEudgrFjl/02YgxbtorRsVoB/3APOTv8abHmfSGos=; b=V5bYQ9KAa8ZW7eate2WrzYDnubxJnWWiqo4di2JKBRyu1WUgcwLWtAAUI2Cjd4ibfS 8H6QlgiNctVrm2g0kPhAkrk6kBaaDg7Vw2i6uPqgy3OecXs3Ceu6GnjNRROthS+cKMix 1AoG63utWoxfmAaY80gduBYhilCGbDKKFVRlTly3GnX3KEg3M/TfOtgCRE1OkBLblkRP 4L6XZV7lMX3VDPwFxq1Fo+9I6REfrTxG4Q2BvRgbkRgkE5WYBGlWvVKAjWP0XG2x4OKR U/D39CMLtleZiJ3KgnsN48MCMZr3B4S3sdEu05YGBzx228cX/X+hHhdtuEdT+YE/7bxU oIjA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:date :message-id:subject:from:to:cc; bh=GWLEudgrFjl/02YgxbtorRsVoB/3APOTv8abHmfSGos=; b=W8O4gyqJwEWHgo1alulDb92zrJ+ok3ZekKvih8HT7nzxB8ug7n04MELuym454peaAl D06ptGacoelm1Md63etWElYerbZkmaVaBDQ0Kkg7fod2bLhZxxEODjI0V6huWG5AX+U/ Lm2XQN5I2LlTixuT9PXThIkAwSnq7W09LVrnfyg+u5qJ3OTX4sc6Z0M3/7X3UzQcm1P2 oTS5o5rfs3ZD0OqPjH4OmDStkhzY9p17elo/DTBeFXK7MfVQykULcXqTD6tPnHPMeUUv 2Rj8Ibxb9/3TmgLL2ZqW3D/QlwsppGjw1f8vcDyeaOJ5fhtJjZKmum6FCE++XaulS+V3 tDaA== X-Gm-Message-State: AOPr4FVrfwPO+CodbHgBbLSDi3Mi9xZTE14X88kLWugrp92+vR8BKgOTBlusOpmu6CLHbq3B9/MbpRbFmCBCNw== MIME-Version: 1.0 X-Received: by 10.50.160.195 with SMTP id xm3mr1944753igb.12.1460685695223; Thu, 14 Apr 2016 19:01:35 -0700 (PDT) Sender: wlosh@bsdimp.com Received: by 10.79.104.197 with HTTP; Thu, 14 Apr 2016 19:01:35 -0700 (PDT) X-Originating-IP: [50.253.99.174] In-Reply-To: <57104251.5080102@mu.org> References: <57104251.5080102@mu.org> Date: Thu, 14 Apr 2016 20:01:35 -0600 X-Google-Sender-Auth: zqdyRvKQ4D9r9R3fxko6KYJlw_I Message-ID: Subject: Re: Heads up From: Warner Losh To: Alfred Perlstein Cc: FreeBSD Current Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.21 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Apr 2016 02:01:36 -0000 On Thu, Apr 14, 2016 at 7:22 PM, Alfred Perlstein wrote: > > > On 4/14/16 3:42 PM, Warner Losh wrote: > >> The CAM I/O scheduler has been committed to current. This work is >> described >> in https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf though the >> default scheduler doesn't change the default (old) behavior. >> >> One possible issue, however, is that it also enables NCQ Trims on ada >> SSDs. >> There are a few rogue drives that claim support for this feature, but >> actually implement data corrupt instead of queued trims. The list of known >> rogues is believed to be complete, but some caution is in order. >> >> Yowch... > > With data at stake wouldn't a whitelist be better along with a tool for > testing it? > > Example, you have whitelist and blacklist, if the device isn't on either > list you output a kernel message and suggest they run a tool to "test" the > controller and report back the findings? The only way to test it is to enable it. Run it for a day or six. If your data goes away, the drive is a lying sack. There's no tool to detect this that I've seen. You run the NCQ trim, it works. You do it again, it works again. After a while, if you have a bad drive model, bad things happen that are drive model specific. Did I mention that the black list matches Linux's black list and that only a tiny number of drive models lie. I guess I didn't. I am thinking of adding a tunable to turn it off though for people that are paranoid. Warner