From owner-freebsd-questions@FreeBSD.ORG Mon Jul 13 17:29:04 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 00189106566B for ; Mon, 13 Jul 2009 17:29:03 +0000 (UTC) (envelope-from mahlerrd@yahoo.com) Received: from web51008.mail.re2.yahoo.com (web51008.mail.re2.yahoo.com [206.190.38.139]) by mx1.freebsd.org (Postfix) with SMTP id 9A1F28FC13 for ; Mon, 13 Jul 2009 17:29:03 +0000 (UTC) (envelope-from mahlerrd@yahoo.com) Received: (qmail 2973 invoked by uid 60001); 13 Jul 2009 17:29:03 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1247506143; bh=Y9FRbpZnNSEG5ELy8SEvv/2GRuOi7larSD1ImSJVMzU=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=PjYodIXY5SFBAeJHILfWrNjQ+jL88OQF6NEbJO4XlRsIFQfsF2bZaV47hdqkuLDM/wD1t5D/8NlhEGRt7+2djoymHMCycqpvV5fDsByHB1eKAmqA+jFBFr1LWoGdv2PfWX1YpGkxx7gsSYbG2APQMhz4G6Lj1jmAZ7PIHot0p1U= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=ZhcCAmfInwvdYgy55pEdNBOuubj5rUWMyk+3htEcyvKdtCHDmxAJsdU5NFInODpsgvKDeIN6QTa3FL+z7DaJk7J9c5I6kWJq8MnmLijG5Y9X1IiFNpSXBiNneFmSymk8fh0S8dpN27NzoC7chsbkSNhWlP+GYJ4mfBiTJGZ7QHU=; Message-ID: <42310.1585.qm@web51008.mail.re2.yahoo.com> X-YMail-OSG: HdYtCtoVM1m5QcRzBgNA9Zm7BKJz4ivEzV7Y4dmI2Lnf0fC.GY3_Fh.VTlAu5VSwlvxhw6h3GWwufmJyMtGNI36WCClz2q7QtQ2qRr5VidQl.Rb5CftrO94267xbnEqlBNPdXkZRcKzpPP4EnpfucK4FOtjS_xwscVQzez9Byh0ghzdAul2PfNbrx_8n9RqaNCBmWUDRmBw3EihUAuZ8I8.DQJbDmYDvkBqaDO5Xpjx3MgdZPpKHVXvyZKdT8a6spVW.nhnRCAHgjQspquYjxbpeLgluDpJ_j.BOU25jRM.SkILeJ9GukHEPnOSi1RQApGdBay1ILg-- Received: from [74.40.57.42] by web51008.mail.re2.yahoo.com via HTTP; Mon, 13 Jul 2009 10:29:02 PDT X-Mailer: YahooMailClassic/5.4.17 YahooMailWebService/0.7.289.15 Date: Mon, 13 Jul 2009 10:29:02 -0700 (PDT) From: Richard Mahlerwein To: Free BSD Questions list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: ZFS or UFS for 4TB hardware RAID6? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: mahlerrd@yahoo.com List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Jul 2009 17:29:04 -0000 --- On Sun, 7/12/09, Maxim Khitrov wrote: > From: Maxim Khitrov > Subject: ZFS or UFS for 4TB hardware RAID6? > To: "Free BSD Questions list" > Date: Sunday, July 12, 2009, 11:47 PM > Hello all, > > I'm about to build a new file server using 3ware 9690SA-8E > controller > and 4x Western Digital RE4-GP 2TB drives in RAID6. It is > likely to > grow in the future up to 10TB. I may use FreeBSD 8 on this > one, since > the release will likely be made by the time this server > goes into > production. The question is a simple one - I have no > experience with > ZFS and so wanted to ask for recommendations of that versus > UFS2. How > stable is the implementation and does it offer any benefits > in my > setup (described below)? > > All of the RAID6 space will only be used for file storage, > accessible > by network using NFS and SMB. It may be split into > separate > partitions, but most likely the entire array will be one > giant storage > area that is expanded every time another hard drive is > added. The OS > and all installed apps will be on a separate software RAID1 > array. > > Given that security is more important than performance, > what would be > your recommended setup and why? > > - Max Your mileage may vary, but... I would investigate either using more spindles if you want to stick to RAID6, or perhaps using another RAID level if you will be with 4 drives for a while. The reasoning is that there's an overhead with RAID 6 - parity blocks are written to 2 disks, so in a 4 drive combination you have 2 drives with data and 2 with parity. With 4 drives, you could get much, much higher performance out of RAID10 (which is alternatively called RAID0+1 or RAID1+0 depending on the manufacturer and on how accurate they wish to be, and on how they actually implemented it, too). This would also mean 2 usable drives, as well, so you'd have the same space available in RAID10 as your proposed RAID6. I would confirm you can, on the fly, convert from RAID10 to RAID6 after you add more drives. If you can not, then by all means stick with RAID6 now! With 4 1 TB drives (for simpler examples) RAID5 = 3 TB available, 1 TB worth used in "parity". Fast reads, slow writes. RAID6 = 2 TB available, 2 TB worth used in "parity". Moderately fast reads, slow writes. RAID10 = 2 TB available, 2TB in duplicate copies (easier work than parity calculations). Very fast reads, moderately fast writes. When you switch to, say, 8 drives, the numbers start to change a bit. RAID5 = 7TB available, 1 lost. RAID6 = 6TB available, 2 lost. RAID10 = 4TB available, 4 lost.