From owner-freebsd-fs@FreeBSD.ORG Tue Feb 23 21:22:12 2010 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 666B0106566B for ; Tue, 23 Feb 2010 21:22:12 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from mail-ew0-f227.google.com (mail-ew0-f227.google.com [209.85.219.227]) by mx1.freebsd.org (Postfix) with ESMTP id 471C48FC15 for ; Tue, 23 Feb 2010 21:22:11 +0000 (UTC) Received: by ewy27 with SMTP id 27so499914ewy.34 for ; Tue, 23 Feb 2010 13:22:04 -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:from:date:x-google-sender-auth:message-id:subject:to:cc :content-type; bh=RyKFr7dvaUo1jSZL4vJjt40nWnggcnM1wC+i0WVqL3Y=; b=Cr47b7YE10H629vMzUKlFHRoO3ZbwcpP0zuIkxiQQcFkrUZsnlYAWBq5zzQx6HF+76 0ENLA84e3CwH3EONjYVr/9643CUqn8REkMd0ryLmd98RUw+7yWfu0pWXyO7bMCOtTleL CHdCFY33OueUSX9UVR+kohbfURFQvmPEMw5IM= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type; b=bt+JqOBiYCsv2RmKaIM4C4VVDQc5qLfFrSsHSBX5G9mp3v5Qbxu301XtngrrDvcvy3 4KtZBFPeq0LIWNh2sveKzcL+EBqXY9zENrSV8kAqdytArL+DUkL5LsVoKbMmmMq9E3UZ Bf+KxFshcdEOCeSGUk2itceHLh+kHjmxhGiuU= MIME-Version: 1.0 Sender: ivoras@gmail.com Received: by 10.216.87.131 with SMTP id y3mr2439861wee.9.1266960122595; Tue, 23 Feb 2010 13:22:02 -0800 (PST) In-Reply-To: <20100223193458.GO13767@cicely7.cicely.de> References: <20100223193458.GO13767@cicely7.cicely.de> From: Ivan Voras Date: Tue, 23 Feb 2010 22:21:41 +0100 X-Google-Sender-Auth: 124dffe60205508d Message-ID: <9bbcef731002231321t352ce3e6y5fdafbf75b7fac54@mail.gmail.com> To: ticso@cicely.de Content-Type: text/plain; charset=UTF-8 Cc: freebsd-fs@freebsd.org Subject: Re: Some ZFS+NFS benchmarks (OpenSolaris) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Feb 2010 21:22:12 -0000 On 23 February 2010 20:34, Bernd Walter wrote: > On Tue, Feb 23, 2010 at 08:15:48PM +0100, Ivan Voras wrote: >> http://staff.science.uva.nl/~delaat/sne-2009-2010/p02/report.pdf >> >> It's curious how ZIL on SSD doesn't help them with NFS when they >> increase the load. > > My assumption is because they already write linear on SSD and get a more > or less fixed write rate, while parallel write rate with disks can > increase because of reordering. > > I'm personally impressed by my own tests on how much our current > USB stack can speed up random reads even with cheap USB flash sticks > used as cache devices. This is surprising to hear - I've just run some randomio (http://www.arctic.org/~dean/randomio/) tests on two little used USB flash sticks and got around 110 IOPS sequential writing (~~ 7 MB/s) and a bit less than 30 IOPS random writes of 4 KB buffers (amounting to ~~ 1 MB/s). (the test command was "randomio file 16 1 1 4096 10"). The ZIL should be written practically linearly - the sequential write rate is relevant here - and it is actually significantly slower than what mechanical HDDs can achieve. Is your result with ZIL perhaps simply because you moved it to another device and so freed the main device?