From owner-freebsd-hackers@FreeBSD.ORG Sat Jan 23 05:19:39 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id BCE361065672 for ; Sat, 23 Jan 2010 05:19:39 +0000 (UTC) (envelope-from artemb@gmail.com) Received: from mail-yx0-f171.google.com (mail-yx0-f171.google.com [209.85.210.171]) by mx1.freebsd.org (Postfix) with ESMTP id 72B288FC0A for ; Sat, 23 Jan 2010 05:19:39 +0000 (UTC) Received: by yxe1 with SMTP id 1so1616780yxe.3 for ; Fri, 22 Jan 2010 21:19:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to:cc :content-type:content-transfer-encoding; bh=pCQEOkQFIyUOy83DZWEOhyAW4+JWKaDGOLL4utN+bB8=; b=DR72wvyv/dquxgYpF8QpG0KW6pjYPDoYP+2NbKJdPJgRKlOIw/Zc6l5JM4fqCrGfNm ney7I7gb856HXnEKXIYn8IaFlwiO7O3g5EFtQlWh5vLGX8Bgaajmgp90YoaV0BQ3iAKW p+0zI0CrJBoondMfIDGRAOggESu5oUq6u9lik= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=kxQtGeNQCIHGLjAQ0f1ySU2CcT6VehNqdmGe+P4WrbrW2cuJIkgjx8ExuHTz1XbhAe hV7Ba2wXb7BiML3LqDkTpu/ihdTDOd117SCUBfibx0K4Om1tdZtDclk1r0MJ9MxAsUjn xSzLojBGQEHpjmTefQ9AHhT+9LHhSYfBiYQgI= MIME-Version: 1.0 Sender: artemb@gmail.com Received: by 10.90.135.14 with SMTP id i14mr3602579agd.24.1264223978625; Fri, 22 Jan 2010 21:19:38 -0800 (PST) In-Reply-To: References: <7f14551c1001190119x46c6b04dx2362cd1252f0d81@mail.gmail.com> <7f14551c1001190216w49814186n1ada2b721380502b@mail.gmail.com> <4B55C5A6.2020109@DataIX.net> <20100120111433.25801pnmhrxnirok@webmail.leidinger.net> Date: Fri, 22 Jan 2010 21:19:38 -0800 X-Google-Sender-Auth: 0409ad67480a1e60 Message-ID: From: Artem Belevich To: jhell Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: Alexander Leidinger , FreeBSD Hackers Subject: Re: Setting "zfs_arc_max" value in FreeBSD 8. X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 23 Jan 2010 05:19:39 -0000 Good to hear that it's usable for you even on a relatively low-memory system. Now, throw in an SSD for L2ARC, more RAM for ARC (and L2ARC housekeeping) and then it starts to really shine. As for better than expected performance, in my not-so scientific benchmarks (copying 10G-large files on 8-disk RAIDZ2 pool until filesystem is full) ZFS on FreeBSD did beat the hell out of OpenSolaris on the same hardware. I was really surprised. I'm sure something needed to be tuned on OpenSolaris, but it was nice to see FreeBSD performing so well. --Artem On Fri, Jan 22, 2010 at 6:39 PM, jhell wrote: > > On Fri, 22 Jan 2010 11:47, fbsdlist@ wrote: >>>> >>>> Anyone know if it is adjustable on a system with 1024MB of ram ? Is th= is >>>> just being auto calculated by some other value ? >> >> You may want to make sure that vm.kmem_size is set to a value much >> larger than vfs.zfs.arc_max. Default value may be too small to allow >> such a large ARC. >> >> On a side note, I'm not sure that ZFS is a good match for system with >> only 1G of RAM. By trial and error on my box with 8G or memory I've >> figured out that I need to set arc_max ~1G below physical memory size >> to avoid lockups under load. YMMV. >> > > ZFS on this box with 1G has been quite enjoyable actually. With the setti= ngs > I have posted I have not had any lockup on stable/7 and no sudden freezes= or > waits for transfers. So this entirely thus far has been a godsend. I had > even put this thing through some of the tortures that others have posted = to > the list and not come up with the same results but better. There is > obviously a lot of variables in this between hardware and configurations > used so the results are minimal in comparison. With ZFS in place on this > machine it performs a little bit under specs for the hardware but I would= n't > expect anything less for such a file-system. > > -- > > =A0Thoughts & Prayers out to Haiti. > > =A0jhell > >