From owner-freebsd-current@FreeBSD.ORG Thu Nov 12 21:39:14 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 13ADC106566C; Thu, 12 Nov 2009 21:39:14 +0000 (UTC) (envelope-from sfourman@gmail.com) Received: from mail-pz0-f185.google.com (mail-pz0-f185.google.com [209.85.222.185]) by mx1.freebsd.org (Postfix) with ESMTP id CE0B78FC1C; Thu, 12 Nov 2009 21:39:13 +0000 (UTC) Received: by pzk15 with SMTP id 15so1835970pzk.3 for ; Thu, 12 Nov 2009 13:39:13 -0800 (PST) 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:cc:content-type :content-transfer-encoding; bh=bCTPPUSYmoH3klX45QwPJiNPWsEnAgle+MAoGnpOxTM=; b=S+JpW9kQ15tjWMN0eHjZ6ici88+uqZwQk9eLtkd2yR2aDMaTbmQfO8HfxpKhELKirK 2SiklporanQ+78eHYC4D+Yxfp3Wa5m5pU9jomMOEbFvJ903es/8PVW2wskdyHkstV099 oxcny51P3Ed12I5ZI7lBNN0b7+p4uW5DJ4uck= 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:content-transfer-encoding; b=uSOWCp97m2l5vpb7Kt4WHKHDfMp6M/sFxVeJry/J8hOj88fxPrJKhvg12abJyuBOFQ 65smGyFOVKU7OUFfiZE0D6fIlR1iFhpUsoSNVeRDbTZcUYR/q9VNHpZgZRkoD/7mH0fe 5vqvNqmbXCorDZwHB+W76pUxPmOtAPxig8TaA= MIME-Version: 1.0 Received: by 10.142.59.16 with SMTP id h16mr404903wfa.161.1258061953340; Thu, 12 Nov 2009 13:39:13 -0800 (PST) In-Reply-To: References: <11167f520911111050j36dd94far667c81e6f5c18e69@mail.gmail.com> <20091111204903.GI89052@dan.emsphone.com> <11167f520911111326v13bb442bt36e853afbecdf834@mail.gmail.com> <9bbcef730911111352t12188bdajbca71bcf35a5beb5@mail.gmail.com> <11167f520911121044l74744c30u5a4d9ca008ab863c@mail.gmail.com> <11167f520911121101o403751ddmb544dfaf1c61bf1e@mail.gmail.com> Date: Thu, 12 Nov 2009 15:39:13 -0600 Message-ID: <11167f520911121339y4161a1a2sae8b6196c3b7a1fb@mail.gmail.com> From: "Sam Fourman Jr." To: Scott Ullrich Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: Rick Macklem , Dan Nelson , Artem Belevich , freebsd-current@freebsd.org, Ivan Voras Subject: Re: Help ZFS FreeBSD 8.0 RC2 Write performance issue X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Nov 2009 21:39:14 -0000 On Thu, Nov 12, 2009 at 3:14 PM, Scott Ullrich wrote: > On Thu, Nov 12, 2009 at 3:19 PM, Artem Belevich wrote: >> >> Log seems to be somewhat weak point in ZFS. If you lose your log >> device, you will lose your pool. Plus, there's no way to remove log >> device from the pool. So, once you attach some device as a log, you'd >> better be sure that device does not disappear, because it will take >> the rest of the pool with it. From that point, real ram-disk (i.e. >> /dev/mdN) is definitely a recipe for disaster. External ramdisk with a >> battery backup may be an option, but even in mirrored configuration >> seems rather risky to me. >> >> http://jmlittle.blogspot.com/2008/05/problem-with-slogs-how-i-lost.html >> >> I'd say that SSD are probably the best fit for slog role. > > Indeed. =A0 I mirrored 2 SSDs on an Areca in case I loose one of them. > Partitioned the SSD into a log device and the rest being cache (see > the ZFS best practices guide for details). > > Needless to say my performance matches that of normal writes and reads > when using NFS now. if you wouldn't mind posting, what kind of NFS performance can you achieve? my application is office Fileserver (the clients are FreeBSD 8 diskless PXE boot) so idk if it is possible to achieve gigabit NFS performance. iperf is able to get ~970mbit from a client to the NFS server. I realize that disk i/o is the limiting factor so I bought 6x SATA2 disks and a Areca card Sam Fourman Jr.