From owner-freebsd-questions@FreeBSD.ORG Mon Jan 27 09:59:31 2014 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id A0E522C2 for ; Mon, 27 Jan 2014 09:59:31 +0000 (UTC) Received: from mail-we0-x232.google.com (mail-we0-x232.google.com [IPv6:2a00:1450:400c:c03::232]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 34E9414BD for ; Mon, 27 Jan 2014 09:59:31 +0000 (UTC) Received: by mail-we0-f178.google.com with SMTP id t60so4886228wes.23 for ; Mon, 27 Jan 2014 01:59:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=Ed9xzUqW1bKvnAvX0OpxMJOS+x/gGBwhcOAHCAZFAJw=; b=AIjWbt+RETIi31mZ41/w6eYCP9cg+CJqjBI8jt9oMfCLISc0rJr9e5W7qSs0pWlJFN fnF9hUcS0ypQi0Blt+SRfbJakB61EMvjJIQaAg1+3KDMcO+Tm1f/OBQQrAWLbUMllHxl h7p/TZrg2ii5Lxw166ZMplzSLLdMS3YMhMd4QEaGqBxxtMVHtYXAB+O6VXBo3HdUnOBM jgVeEqAV6r199khFXjyedphEhxiZNrnkJCExZkJQfeJh2rznS33SbUuRJ7MMxY0Nw0MM WJcF6quO7tjtWjNHj8E0HDbmuiWr9cJJRSAGKVXv9acYU8rvnncomPsftnVzN29TFLoK cUqQ== X-Received: by 10.194.241.228 with SMTP id wl4mr19797511wjc.2.1390816769587; Mon, 27 Jan 2014 01:59:29 -0800 (PST) Received: from x220.optiplex-networks.com (81-178-2-118.dsl.pipex.com. [81.178.2.118]) by mx.google.com with ESMTPSA id eo4sm26496208wib.9.2014.01.27.01.59.28 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 27 Jan 2014 01:59:29 -0800 (PST) Message-ID: <52E62DFF.3010600@gmail.com> Date: Mon, 27 Jan 2014 09:59:27 +0000 From: Kaya Saman User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: =?ISO-8859-1?Q?Trond_Endrest=F8l?= Subject: Re: ZFS confusion References: <52E40C82.7050302@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Cc: freebsd-questions X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Jan 2014 09:59:31 -0000 Many thanks Trond for the response.... I was getting worried for a sec there :-) On 01/27/2014 09:08 AM, Trond Endrestøl wrote: > On Sat, 25 Jan 2014 19:12-0000, Kaya Saman wrote: > > [...] > No one's answered this, so I'll just give you my 2 cents. > > Triple parity means you're using storage capacity equivalent of three > drives for parity alone. If you use five drives in total, this gives > you 2 drives worth of real data and 3 drives worth of parity. In other > words, you should really consider using a lot more drives when using > triple parity, say nine drives. So, basically if I have (just as silly example); 5x drives of 100MB capacity, this would equal 500MB in total. Meaning that only 200MB would be usable..... Having just done a quick experiment: zpool create test_pool raidz3 /tmp/disk1 /tmp/disk2 /tmp/disk3 /tmp/disk4 /tmp/disk5 I get: test_pool 476M 304K 476M 0% 1.00x ONLINE - then writing a 300M file to pool: dd if=/dev/zero of=/test_pool/file bs=300M count=1 dd: /test_pool/file: No space left on device test_pool 476M 396M 79.8M 83% 1.00x ONLINE - du -sch /test_pool/file 157M /test_pool/file 157M total > > So I guess, now I have to ask; when building a disk pool, what's the best option to go for between capacity and redundancy? In my case I gradually want to expand my storage when I need it, so to maximize capacity RAID0 would be the easiest. This doesn't give me any redundancy however, unless I use RAID1+0 but then I loose physical capacity due to the mirrors. Would it be better to create a raidz1 pool then just add raidz1 pools to the master as time goes by? As in: zpool create test_pool raidz1 /tmp/disk1 /tmp/disk2 /tmp/disk3 /tmp/disk4 /tmp/disk5 zpool add test_pool raidz1 /tmp/disk6 /tmp/disk7 /tmp/disk8 /tmp/disk9 /tmp/disk10 dd if=/dev/zero of=/test_pool/file bs=600M count=1 1+0 records in 1+0 records out 629145600 bytes transferred in 190.069986 secs (3310073 bytes/sec) Then running a 'zpool list' gets: test_pool 952M 751M 201M 78% 1.00x ONLINE - So virtually out of: NAME STATE READ WRITE CKSUM test_pool ONLINE 0 0 0 raidz1-0 ONLINE 0 0 0 /tmp/disk1 ONLINE 0 0 0 /tmp/disk2 ONLINE 0 0 0 /tmp/disk3 ONLINE 0 0 0 /tmp/disk4 ONLINE 0 0 0 /tmp/disk5 ONLINE 0 0 0 raidz1-1 ONLINE 0 0 0 /tmp/disk6 ONLINE 0 0 0 /tmp/disk7 ONLINE 0 0 0 /tmp/disk8 ONLINE 0 0 0 /tmp/disk9 ONLINE 0 0 0 /tmp/disk10 ONLINE 0 0 0 errors: No known data errors I have 8 disks usable with 2x disks for parity.... if my understanding is correct. Regards, Kaya