From owner-freebsd-fs@FreeBSD.ORG Thu Mar 27 09:16:10 2014 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 65B284E2 for ; Thu, 27 Mar 2014 09:16:10 +0000 (UTC) Received: from mail-yk0-x22d.google.com (mail-yk0-x22d.google.com [IPv6:2607:f8b0:4002:c07::22d]) (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 27519390 for ; Thu, 27 Mar 2014 09:16:10 +0000 (UTC) Received: by mail-yk0-f173.google.com with SMTP id 10so1981168ykt.4 for ; Thu, 27 Mar 2014 02:16:09 -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=72SjRSzNl50lfE+hu5NB2A54KlxKZpuoLl7T0FeaWRQ=; b=B+RN4OiEY+xUjmS1FfsdLrLa+q75yOH+TlbWqAT232hZDdYRyUiLDk+XbbJp3IddMI cVx0g7pqrAS/izkqL2NWeoLPqWxlTc9r5MY8NA8QKORgNkYkNFtx0IiSypS+GGjfKPRw dyG6Y96a8MhALrpOCIYqdZuL5fzV6n3MEfGbuUibF5HZbycNsVwfQyyJ1P7dSdjvgkz4 ekN/p1r9WeHAhB4paEcxEL59RfqzUOeEmJ93F2I8xh1siG/el42wTLEXjPZ8Yo063qX0 lyhfj/xF4wu/AkuEJZnaC/SiRgyLwUywxrt6oA+6o/TrUXTLLBUnyWIRaHQcm43lTWEe 0q/Q== MIME-Version: 1.0 X-Received: by 10.236.69.230 with SMTP id n66mr80155yhd.124.1395911769183; Thu, 27 Mar 2014 02:16:09 -0700 (PDT) Received: by 10.170.54.17 with HTTP; Thu, 27 Mar 2014 02:16:09 -0700 (PDT) In-Reply-To: References: Date: Thu, 27 Mar 2014 09:16:09 +0000 Message-ID: Subject: Re: zfs l2arc warmup From: krad To: Joar Jegleim Content-Type: text/plain; charset=ISO-8859-1 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: Thu, 27 Mar 2014 09:16:10 -0000 not sure if its made it into freebsd yet but https://www.illumos.org/issues/3525 On 27 March 2014 07:50, Joar Jegleim wrote: > 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 :) > > > -- > ---------------------- > Joar Jegleim > Homepage: http://cosmicb.no > Linkedin: http://no.linkedin.com/in/joarjegleim > fb: http://www.facebook.com/joar.jegleim > AKA: CosmicB @Freenode > > ---------------------- > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >