From owner-freebsd-fs@FreeBSD.ORG Wed Mar 5 07:24:19 2014 Return-Path: Delivered-To: freebsd-fs@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 1CECEDDF for ; Wed, 5 Mar 2014 07:24:19 +0000 (UTC) Received: from mail-we0-f176.google.com (mail-we0-f176.google.com [74.125.82.176]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id A5BF2AE for ; Wed, 5 Mar 2014 07:24:18 +0000 (UTC) Received: by mail-we0-f176.google.com with SMTP id x48so697045wes.35 for ; Tue, 04 Mar 2014 23:24:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=l86piV3ViEfX7qiig6f0oiP9T+xApbm5dt+CYOHiB2U=; b=RbFHJrOCfaaS7I0RMeBDnTy1LNtZV1iW1m51wEg08520zgDSZqvJtgLl2QxKS6D9tZ wYuJOjNHSvobYnIsQifeyDXajVoMcTRA+05Yrjga8ShjXU3497axHwvhuHt44QjvoSpI bJ134ILSe/Hztd8ZQRzM5e7xxLA+6+HSyzHK0b9tX/mqi4YUjwmFSfTiUVRbTLA0hVGb U49yIdZVnO7OUunE1AKaUrHM22vzxxLUI9NErJqu1wPKkPC97G2pr4IvSxIqsTAyrBZd qGoqAU9w/d1BaOXcG0avqTn4uEfa0OZyW1v8P3/kL5BHpOQ7vgeUHEAlyDzSkvxzEGw7 wTQA== X-Gm-Message-State: ALoCoQlFKcJ15tjtLirmOBpGx2k0m8NbbsWP7Mm1wNdFbD9PueIHJwLK0NSLx4IxkNA/0ZV2tegz MIME-Version: 1.0 X-Received: by 10.194.250.34 with SMTP id yz2mr6043910wjc.18.1394003827632; Tue, 04 Mar 2014 23:17:07 -0800 (PST) Received: by 10.227.92.198 with HTTP; Tue, 4 Mar 2014 23:17:07 -0800 (PST) In-Reply-To: References: <53157CC2.8080107@FreeBSD.org> <5315D446.3040701@freebsd.org> Date: Wed, 5 Mar 2014 08:17:07 +0100 Message-ID: Subject: Re: Is LZ4 compression of the ZFS L2ARC available in any RELEASE/STABLE? From: Olav Gjerde To: Bob Friesenhahn Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.17 Cc: freebsd-fs@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Mar 2014 07:24:19 -0000 Currently I've set the recordsize to 8k, however I'm thinking maybe a recordsize of 4k may more optimal? This is because the compressratio with LZ4 is around 2.5 and this value has been constant for all my data while growing from a few megabytes to a tenfold of gigabytes. Maybe something I should play with to see if it makes a difference. On Wed, Mar 5, 2014 at 3:40 AM, Bob Friesenhahn < bfriesen@simple.dallas.tx.us> wrote: > On Tue, 4 Mar 2014, Olav Gjerde wrote: > > I managed to mess up who I replied to and Matthew replied back with a go= od >> answer which I think didn't reach the mailing list. >> >> I actually have a problem with query performance in one of my databases >> related to running PostgreSQL on ZFS. Which is why I'm so interested in >> compression for the L2ARC Cache. The problem is random IO read were >> creating a report were I aggregate 75000 rows takes 30 minutes!!! The >> table >> that I query has 400 million rows though. >> The dataset easily fit in memory, so if I run the same query again it >> takes >> less than a second. >> > > Make sure that your database is on a filesystem with zfs block-size > matching the database block-size (rather than 128K). Otherwise far more > data may be read than needed, and likewise, writes may result in writing > far more data than needed. > > Regardless, L2ARC on SSD is a very good idea for this case. > > Bob > -- > Bob Friesenhahn > bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen= / > GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ > --=20 Olav Gr=F8n=E5s Gjerde