From owner-freebsd-fs@FreeBSD.ORG Thu Mar 27 20:20:13 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 9C8A1EED for ; Thu, 27 Mar 2014 20:20:13 +0000 (UTC) Received: from mail-wg0-x229.google.com (mail-wg0-x229.google.com [IPv6:2a00:1450:400c:c00::229]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 37BF5F4D for ; Thu, 27 Mar 2014 20:20:13 +0000 (UTC) Received: by mail-wg0-f41.google.com with SMTP id n12so2872976wgh.12 for ; Thu, 27 Mar 2014 13:20:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=S0IStkZ867pcl+a7Fqu/PYFr8Dvsz0CADaG/sokK6sA=; b=bAStjR3LGGxHt1AZkWmQpzz85Y/DgxynBhda98+HefpmHsn3C79cRdaWsdT7ABjyRn D7XYj6YtPsk5JQGLFvDSDZpWG/pMlcfQtXITg7wcSuyuD4zCFs/pCRdJJjHlGCyDWA6k GFG1x/F0pvTV+/I95skcDwNGBQWfDOyN2qWTLjgDbphTZl8K9u9xWsMEhLmfSJSjJUOR /qLLW6VgvjGk3mWM3qjy6lM1UHE8Do0cNhybgZddaPJ82e/qG0uhmGkTv1bDMpP6WsJ/ hLTv4GmNfntIA2qLTbRyxUfgiPbfCGcBUUT9gspij7U/A+vfvqNXEevHmKz1PPivs9th Jj0g== MIME-Version: 1.0 X-Received: by 10.180.38.110 with SMTP id f14mr8576091wik.0.1395951611356; Thu, 27 Mar 2014 13:20:11 -0700 (PDT) Received: by 10.216.146.195 with HTTP; Thu, 27 Mar 2014 13:20:11 -0700 (PDT) In-Reply-To: <5333FB8F.7010500@gmail.com> References: <5333FB8F.7010500@gmail.com> Date: Thu, 27 Mar 2014 21:20:11 +0100 Message-ID: Subject: Re: zfs l2arc warmup From: Joar Jegleim To: Johan Hendriks Content-Type: text/plain; charset=UTF-8 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: Thu, 27 Mar 2014 20:20:13 -0000 thnx ! Read the first links many times before, but the second one was new to me and great reading ! On 27 March 2014 11:21, Johan Hendriks wrote: > Joar Jegleim schreef: > >> Hi list ! >> >> I struggling to get a clear understanding of how the l2arc get warm ( >> zfs). >> It's a FreeBSD 9.2-RELEASE server. >> >> From various forum I've come up with this which I have in my >> /boot/loader.conf >> # L2ARC tuning >> # Maximum number of bytes written to l2arc per feed >> # 8MB (actuall=vfs.zfs.l2arc_write_max*(1000 / vfs.zfs.l2arc_feed_min_ms)) >> # so 8MB every 200ms = 40MB/s >> vfs.zfs.l2arc_write_max=8388608 >> # Mostly only relevant at the first few hours after boot >> # write_boost, speed to fill l2arc until it is filled (after boot) >> # 70MB, same rule applys, multiply by 5 = 350MB/s >> vfs.zfs.l2arc_write_boost=73400320 >> # Not sure >> vfs.zfs.l2arc_headroom=2 >> # l2arc feeding period >> vfs.zfs.l2arc_feed_secs=1 >> # minimum l2arc feeding period >> vfs.zfs.l2arc_feed_min_ms=200 >> # control whether streaming data is cached or not >> vfs.zfs.l2arc_noprefetch=1 >> # control whether feed_min_ms is used or not >> vfs.zfs.l2arc_feed_again=1 >> # no read and write at the same time >> vfs.zfs.l2arc_norw=1 >> >> But what I really wonder is how does the l2arc get warmed up ? >> I'm thinking of 2 scenarios: >> >> a.: when arc is full, stuff that evict from arc is put over in l2arc, >> that means that files in the fs that are never accessed will never end >> up in l2arc, right ? >> >> b.: zfs run through fs in the background and fill up the l2arc for any >> file, regardless if it has been accessed or not ( this is the >> 'feature' I'd like ) >> >> I suspect scenario a is what really happens, and if so, how does >> people warmup the l2arc manually (?) >> I figured that if I rsync everything from the pool I want to be >> cache'ed, it will fill up the l2arc for me, which I'm doing right now. >> But it takes 3-4 days to rsync the whole pool . >> >> Is this how 'you' do it to warmup the l2arc, or am I missing something ? >> >> The thing is with this particular pool is that it serves somewhere >> between 20 -> 30 million jpegs for a website. The front page of the >> site will for every reload present a mosaic of about 36 jpegs, and the >> jpegs are completely randomly fetched from the pool. >> I don't know what jpegs will be fetched at any given time, so I'm >> installing about 2TB of l2arc ( the pool is about 1.6TB today) and I >> want the whole pool to be available from the l2arc . >> >> >> Any input on my 'rsync solution' to warmup the l2arc is much appreciated >> :) >> >> > A nice blog about the L2ARC > > https://blogs.oracle.com/brendan/entry/test > > https://blogs.oracle.com/brendan/entry/l2arc_screenshots > > regards > Johan -- ---------------------- Joar Jegleim Homepage: http://cosmicb.no Linkedin: http://no.linkedin.com/in/joarjegleim fb: http://www.facebook.com/joar.jegleim AKA: CosmicB @Freenode ----------------------