From owner-freebsd-questions@FreeBSD.ORG Mon Sep 17 10:36:34 2012 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id C3967106566C for ; Mon, 17 Sep 2012 10:36:34 +0000 (UTC) (envelope-from jamie@kode5.net) Received: from kontrol.kode5.net (kontrol.kode5.net [80.229.5.32]) by mx1.freebsd.org (Postfix) with ESMTP id 31D688FC12 for ; Mon, 17 Sep 2012 10:36:33 +0000 (UTC) Received: from kontrol.kode5.net (localhost [127.0.0.1]) by kontrol.kode5.net (8.14.5/8.14.5) with ESMTP id q8HAaWJQ025869 for ; Mon, 17 Sep 2012 11:36:32 +0100 (BST) (envelope-from jamie@kode5.net) Received: (from jamie@localhost) by kontrol.kode5.net (8.14.5/8.14.5/Submit) id q8HAaWEC025868 for freebsd-questions@freebsd.org; Mon, 17 Sep 2012 11:36:32 +0100 (BST) (envelope-from jamie@kode5.net) X-Authentication-Warning: kontrol.kode5.net: jamie set sender to jamie@kode5.net using -f Date: Mon, 17 Sep 2012 11:36:32 +0100 From: Jamie Paul Griffin To: freebsd-questions@freebsd.org Message-ID: <20120917103632.GA25763@kontrol.kode5.net> Mail-Followup-To: freebsd-questions@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline x-operating-system: FreeBSD 9.1-PRERELEASE amd64 x-pgp-fingerprint: A4B9 E875 A18C 6E11 F46D B788 BEE6 1251 1D31 DC38 x-pgp-key: 1D31DC38 User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: clamav-milter 0.97.5 at kontrol.kode5.net X-Virus-Status: Clean Subject: Questions about ZFS Tuning X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 Sep 2012 10:36:34 -0000 Hi When I installed FreeBSD on my Lenovo Think Center Desktop I created a full ZFS Root file system using Matthew Seaman's excellent article: http://www.infracaninophile.co.uk/articles/install-on-zfs/ My system now is: /home/jamie $ uname -a FreeBSD kontrol.kode5.net 9.1-PRERELEASE FreeBSD 9.1-PRERELEASE #4 r240560: Sun Sep 16 18:40:56 BST 2012 root@kontrol.kode5.net:/usr/src/sys/amd64/compile/KONTROL amd64 I've been wondering about ZFS tuning and have read some articles, including the FreeBSD handbook and wiki articles and also some posts in the FreeBSD forum. The FreeBSD handbook [http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/filesystems-zfs.html], section 21.2.1.3 Loader Tunables suggests adding tunables to /boot/loader.conf for ALL architectures - which I tested: vm.kmem_size="330M" vm.kmem_size_max="330M" vfs.zfs.arc_max="40M" vfs.zfs.vdev.cache.size="5M" However, when I rebooted, although it did boot up ok dmesg showed a complaint from ZFS about vm.kmem_size_max being less than 512mb. So I removed it. The only line relating to ZFS tunables in my /boot/loader.conf file is now: vfs.zfs.prefetch_disable=0 To stop this email becoming too long winded, what I'm interested in is are there entries I need/should/recommend to add to /boot/loader.conf to tune ZFS properly and/or Kernel config options I need/should/recommended to add to my custom Kernel. I have 2GB RAM, and I've set up 2GB GEOM Mirrored Swap. I'm only using one HDD on the machine so it's a fairly basic setup on this machine. Maybe I don't need to do/add anything at all? Would anyone be kind enough to provide some guidance about this? Best Wishes, Jamie.