From owner-freebsd-stable@FreeBSD.ORG Fri May 1 23:28:42 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6F8FB106566C for ; Fri, 1 May 2009 23:28:42 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.28]) by mx1.freebsd.org (Postfix) with ESMTP id 262C88FC12 for ; Fri, 1 May 2009 23:28:41 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: by yw-out-2324.google.com with SMTP id 9so1637588ywe.13 for ; Fri, 01 May 2009 16:28:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=0jXWzrALbfP8oqUpVld0l56GZkP6WD8vZNMDsO9Gd3U=; b=ccoI2pnoMnxV+rmeqCaHTCZjZxZoEH/5EfrtLI8nksdlhcarucDrprwFAJlbMQjO+L v9Fpw+5QFay0tZbBPrp194HPlvFPWWs7Nbto3D8vnT6p0oOdF+VmHPsso1ZcP31kHYWl gKqxYqatZEOWhTA6WyzjGQ4P45h2mCuL6N42k= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; b=xlB82vZr3XMlsiiB4288QzGkBrocVRCIUJzlEDeAiPrP/fqxX1ah+MNKGN+WW2HDTs 1vhP33OvM+OHOxgXl2eHvF/2gEEM3J9dursI6wUjqIrxYNBFNtXjc68x03p4nF+I82Ti DZI16fefe/o0WX+2AK/K6VJEmVnPz/i/QMyWk= MIME-Version: 1.0 Received: by 10.150.136.12 with SMTP id j12mr6684841ybd.46.1241220520975; Fri, 01 May 2009 16:28:40 -0700 (PDT) In-Reply-To: <32A0BDD9-ACF8-43F4-8D2C-0FC151F1D7CB@cryptomonkeys.org> References: <32A0BDD9-ACF8-43F4-8D2C-0FC151F1D7CB@cryptomonkeys.org> Date: Fri, 1 May 2009 16:28:40 -0700 Message-ID: From: Freddie Cash To: FreeBSD Stable Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: current zfs tuning in RELENG_7 (AMD64) suggestions ? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 May 2009 23:28:42 -0000 On Fri, May 1, 2009 at 4:12 PM, Louis Kowolowski wrote: > On May 1, 2009, at 1:53 PM, Pete French wrote: >> ... >> The tuning isn't there to improve performance, it's there to prevent >> the box going titus due to a panic when the ARC gets too big, and >> you are missing the mian one, which is to limit the size of the ARC. >> On recent versions of BSD (and you are running 7.2, so thats fine) then >> the defaults for kmem size are fine, but you still need something like >> this: >> >> vfs.zfs.arc_max=3D"256M" >> >> In there to stop the ARC growing. thats the only tuning I have on >> my 4 gig machine, which takes a steady stream of data and is used >> for taking backup snapshots. ZFS is excellent, and for me is perfectly >> stable, to the point where I am starting to roll it out to production >> machines, with the above tuning. >> > I agree, although I'm using 384 instead of 256. =C2=A0My systems have bee= n > running in production for almost a year now w/o any ZFS issues. The exact value to use will depend on the system. Particularly on the amount of RAM in the system, and what kmem_max is set to. A "rule-of-thumb" we've been using is: kmem_max should be half of the amount of RAM (or 1.5 GB as that's the current max) arc_max should be half of kmem_max Using those, we've been able to run our ZFS boxes without any kmem panics, even when doing rsync backups for 102 remote servers every night to a single box. Finding those values was fun. :( --=20 Freddie Cash fjwcash@gmail.com