From owner-freebsd-stable@FreeBSD.ORG Mon Mar 28 14:32:30 2011 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 638C61065675 for ; Mon, 28 Mar 2011 14:32:30 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: from mail-yw0-f54.google.com (mail-yw0-f54.google.com [209.85.213.54]) by mx1.freebsd.org (Postfix) with ESMTP id 1CBA68FC20 for ; Mon, 28 Mar 2011 14:32:29 +0000 (UTC) Received: by ywf9 with SMTP id 9so1342351ywf.13 for ; Mon, 28 Mar 2011 07:32:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=UZDD8qIbM7BZbzZUxA7AlwTbF0OoFGWj3MO2GtVX07g=; b=HMu2vJ2eD1qBbzVWTya/wD39GGvRMgkedU9W5sWpQP7KsfLkGtdjy99Wb1UztcqPho 03RC2xJ+ecp7B5i5pLrz2DOcVGXP5Vtd+Km5Q9ZF+C9CY9LvGHtwbxq2eaAEYP5DruKh nini05w/9OP8cI0HBk9a/MfnzKnrg9cNxDqZg= 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 :cc:content-type; b=od1OWk7qtZiv2bTSi87RPzlZUu5Y2Af/KTjwqE1Y9mhoww24Vhs3mJzlWzdFIH4Lv/ rmqznqK2d2/Hhwi28U8s9ScY9mrCTcDWMMFgYMSWzrQ5l4m8eOU377FA7I9UcbG/rKF6 AvESw8v9FpTGUuuULhW3/bX/d8I4pJ+5+FYEY= MIME-Version: 1.0 Received: by 10.91.32.2 with SMTP id k2mr3555796agj.19.1301322749256; Mon, 28 Mar 2011 07:32:29 -0700 (PDT) Received: by 10.90.100.10 with HTTP; Mon, 28 Mar 2011 07:32:29 -0700 (PDT) In-Reply-To: References: Date: Mon, 28 Mar 2011 07:32:29 -0700 Message-ID: From: Freddie Cash To: Claus Guttesen Content-Type: text/plain; charset=UTF-8 Cc: FreeBSD Stable Subject: Re: zfs, nfs and zil 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: Mon, 28 Mar 2011 14:32:30 -0000 On Mon, Mar 28, 2011 at 4:22 AM, Claus Guttesen wrote: > I've setup a server with FreeBSD 8.2 (prerelase) and patched zfs to > ver. 28. The server has 11 disks each 2 TB in raidz2. The performance > is very good and I've got approx. 117 MB/s on plain GB nics using > iscsi. > > I'm mounting the FreeBSD-server from a couple of vmware esxi 4.1 > servers using nfs, but when there is alot of i/o the server becomes > unresponsive, easily triggered by installing ie. ms-sql. The server > itself is up but is not reachable from the network. When I take the > nic down and up again connection to the network is reestablished > (ip-wise). > > A friend of mine has suggested that I disable the zil. The page > http://wiki.freebsd.org/ZFSTuningGuide says 'Disabling ZIL is not > recommended where data consistency is required (such as database > servers) but will not result in file system corruption.' > > Has anyone tried to disable zil and achieved better performance and > still maintain a consistent filesystem? If your disk controller has a lot of cache on it, and a battery backup, then enabling the write cache and disabling the ZIL can be faster, without sacrifising consistency (the write cache on the controller acts like a ZIL). There's several threads on the zfs-discuss mailing list where this is discussed. However, the better solution, and the one most recommended for those using NFS with ZFS, is to install a small, write-optimised, SLC-based SSD to the system as a separate log (SLOG/ZIL) device. NFS is a very sync-heavy protocol, and having a super-fast ZIL sitting on a separate SSD will greatly improve things. -- Freddie Cash fjwcash@gmail.com