From owner-freebsd-fs@FreeBSD.ORG Fri Jul 6 01:16:48 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A31CE106566B for ; Fri, 6 Jul 2012 01:16:48 +0000 (UTC) (envelope-from jusher71@yahoo.com) Received: from nm18-vm0.bullet.mail.ne1.yahoo.com (nm18-vm0.bullet.mail.ne1.yahoo.com [98.138.91.37]) by mx1.freebsd.org (Postfix) with SMTP id 4D0818FC12 for ; Fri, 6 Jul 2012 01:16:48 +0000 (UTC) Received: from [98.138.90.54] by nm18.bullet.mail.ne1.yahoo.com with NNFMP; 06 Jul 2012 01:16:42 -0000 Received: from [98.138.88.235] by tm7.bullet.mail.ne1.yahoo.com with NNFMP; 06 Jul 2012 01:16:42 -0000 Received: from [127.0.0.1] by omp1035.mail.ne1.yahoo.com with NNFMP; 06 Jul 2012 01:16:42 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 727934.90293.bm@omp1035.mail.ne1.yahoo.com Received: (qmail 58422 invoked by uid 60001); 6 Jul 2012 01:16:42 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1341537402; bh=/jk72BvB3MnENaivEqEqMvHMFgE1ZvqzjK0Qom9+ujU=; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Subject:To:MIME-Version:Content-Type; b=R1q1EX9XorofVMzoAkn0Xap8hl3PRFOOIc/82Ptcu32CcuVuCxIMZxpnm96GcYjMCYK/p94+2xwOEkP810gfiYmCK+JW3U79XdgtHhZUht8k3vo5/Kk7UQiODGzQl3sVGj5c7d6FHjeSYLBJuK+D5Qe0pbGZMJ+CPI7peys3phg= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:Message-ID:Date:From:Subject:To:MIME-Version:Content-Type; b=Nw2x9Fg0bwb9CZNdcWktOJ/5sdZWWPx8RNjzKc/YMQeq2gK18RBWZUpf/uX/7v0FmLr4h+ujq3Yo4Tfz7BMOQFZVJwNQy8ii+UWn6n2XFmpPYwKCcEbVRiXa5LNJqhK2NcurL8QKzgVk588UbmRt+TxCGt+G2UQMV8J9b3hIDms=; X-YMail-OSG: Usm.hq4VM1ldUMzxci51p_.iFa4uX50KVILTV_PImGxVcZ7 WhGJSRqbg4qYtgV9KF0hi.mi6UEqznW6qoJFfIQmcxm0BNrumd9TpZ8SKUcC 4uDY8kd6O2baFDpNaVX4Mam49olXpWOKB8OJD87WxYNd4uMK2csZgrMbFXmS qPCo_bzWAzTKyTQ4bERu8QADO8Dwgu8Sis3HJD942REzFXptNGCYjl1MMIZU onXSprE4BQkzzKlhstKgLkWXYLybmrzGSD2ZzzmMckNIsHVp4kh0U0.GPhU8 H5ig6WiXQ1YdvgdsZ.T7OoiZi.fjdjZGeI3lNdAI5dsFSFYq5fTl9cEYfPn9 1kopuserwZpegF6P5fJzAQzUyUon.8_Itb965oHW8eY2HN8ozswFw.AnmCXX 1HA-- Received: from [166.217.14.237] by web122504.mail.ne1.yahoo.com via HTTP; Thu, 05 Jul 2012 18:16:42 PDT X-Mailer: YahooMailClassic/15.0.8 YahooMailWebService/0.8.118.349524 Message-ID: <1341537402.58301.YahooMailClassic@web122504.mail.ne1.yahoo.com> Date: Thu, 5 Jul 2012 18:16:42 -0700 (PDT) From: Jason Usher To: freebsd-fs@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailman-Approved-At: Fri, 06 Jul 2012 01:53:56 +0000 Subject: vdev/pool math with combined raidzX vdevs... 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: Fri, 06 Jul 2012 01:16:48 -0000 It's easy to find the failure math for raidz2 and raidz3. But what if you create a pool with 3 different raidz3 vdevs inside of it ? For instance, 3 12-drive raidz3 vdevs in one big pool. For each individual vdev the failure probability is now higher, since not only will it fail when 4 drives in the vdev fail, but it will also fail if four drives in any of the other two vdevs fail. So each raidz3 vdev now has a failure rate higher than vanilla raidz3 ... but what is that new failure rate ? Is it still higher than vanilla raidz2 ?