From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 71A511381F3 for ; Thu, 19 Sep 2013 12:54:39 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 5C3E7E0BBE; Thu, 19 Sep 2013 12:54:29 +0000 (UTC) Received: from svr-us4.tirtonadi.com (svr-us4.tirtonadi.com [69.65.43.212]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 5E1D2E0B0E for ; Thu, 19 Sep 2013 12:54:28 +0000 (UTC) Received: from mail-vb0-f42.google.com ([209.85.212.42]:39078) by svr-us4.tirtonadi.com with esmtpsa (TLSv1:RC4-SHA:128) (Exim 4.80.1) (envelope-from ) id 1VMdkc-001jjX-8Y for gentoo-user@lists.gentoo.org; Thu, 19 Sep 2013 19:54:30 +0700 Received: by mail-vb0-f42.google.com with SMTP id e12so6548868vbg.29 for ; Thu, 19 Sep 2013 05:54:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=sqQL4fmvV8Djwl7mLxrquj4i/1MFiUMfYL6xvIrZvrY=; b=Kna3ASakTJY2xcYDivppUn/ceGeCynFpauZ5O0ixJbBj6SBGkPeCAciNjGgkIs9tI7 bQnkclZn6fk3GtoVTTsW1dXC/5T/3rlFDNPFew3kSTxCCiUXaBSD31E1j2SpMA3BGz6E UTWFnodTTpHSwi+1ibNFFg6pnKrn/OLwi/+8Zyv84OA0MbMmGTNRho1rGsd1X+0n+Q0G bIBmyCNRaUomMEXNupTC3jFPWzR1wtEJ8FYyM3vg2txxJIXY0rGn2xdxxkrv62wHayAJ Ms9egjXYcS2lsrqS10DuozPt6JyBbnncn8ZxcupYQDNPxYTKF0KRyMpXRxtKL/Dv1Dum oCaw== Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 X-Received: by 10.220.13.20 with SMTP id z20mr1112630vcz.0.1379595265423; Thu, 19 Sep 2013 05:54:25 -0700 (PDT) Received: by 10.220.163.69 with HTTP; Thu, 19 Sep 2013 05:54:25 -0700 (PDT) In-Reply-To: <523AD3F2.40301@libertytrek.org> References: <523898A3.7000404@googlemail.com> <52389B55.6090600@libertytrek.org> <20130918042228.GG25579@server> <20130919074441.GB12275@TranscendTheRubicon.fritz.box> <523AD3F2.40301@libertytrek.org> Date: Thu, 19 Sep 2013 19:54:25 +0700 Message-ID: Subject: Re: [gentoo-user] Re: ZFS From: Pandu Poluan To: gentoo-user Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - svr-us4.tirtonadi.com X-AntiAbuse: Original Domain - lists.gentoo.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - poluan.info X-Get-Message-Sender-Via: svr-us4.tirtonadi.com: authenticated_id: rileyer+pandu.poluan.info/only user confirmed/virtual account not confirmed X-Archives-Salt: 2250b9e0-c3b9-44a1-9635-fed7e3a145e7 X-Archives-Hash: f3cdd4d9bde20cdb4674e23377d3a73b On Thu, Sep 19, 2013 at 5:37 PM, Tanstaafl wrot= e: > On 2013-09-19 3:44 AM, Hinnerk van Bruinehsen >> You should definitely determine the right value for ashift on pool >> creation >> (it controls the alignment on the medium). It's an option that you afaik >> can only set >> on filesystem creation and therefore needs a restart from scratch if you >> get it >> wrong. >> According to the illumos wiki it's possible to run a mixed pool (if you >> have >> drives requiring different alignments[1]) >> If in doubt: ask ryao (iirc given the right information he can tell you >> which >> are the right options for you if you can't deduce it yourself). >> Choosing the wrong alignment can cause severe performance loss (that's n= ot >> a ZFS issue but happened when 4k sector drives appeared and tools like >> fdisk >> weren't aware of this). > > > Yikes... > > Ok, shouldn't there be a tool or tools to help with this? Ie, boot up on = a > bootable tools disk on the system with all drives connected, then let it > 'analyze' your system, maybe ask you some questions (ie, how you will be > configuring the drives/RAID, etc), then spit out an optimized config for > you? > > It is starting to sound like you need to be a dang engineer just to use > ZFS... > Just do ashift=3D12 and you're good to go. No need to analyze further. The reason I said that because in the future, *all* drives will have 4 KiB sectors. Currently, many drives still have 512 B sectors. But when one day your drive dies and you need to replace it, will you be able to find a drive with 512 B sectors? Unlikely. That's why, even if your drives are currently of the 'classic' 512 B ones, go with ashift=3D12 anyway. For SSDs, the situation is murkier. Many SSDs 'lie' about their actual sector size, reporting to the OS that their sector size is 512 B (or 4 KiB). No tool can pierce this veil of smokescreen. The only way is to do research on the Internet. IIRC, a ZFS developer has embedded -- or planned to embed -- a small database into the ZFS utilities to conclusively determine what settings will be optimal. I forgot who exactly. Maybe @ryao can pipe in (hello Richard! If you're watching this thread, feel free to add more info). Rgds, --=20 FdS Pandu E Poluan ~ IT Optimizer ~ =E2=80=A2 LOPSA Member #15248 =E2=80=A2 Blog : http://pepoluan.tumblr.com =E2=80=A2 Linked-In : http://id.linkedin.com/in/pepoluan