From owner-freebsd-stable@FreeBSD.ORG Wed Jan 5 15:55:13 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1159B106564A for ; Wed, 5 Jan 2011 15:55:13 +0000 (UTC) (envelope-from cforgeron@acsi.ca) Received: from mta01.eastlink.ca (mta01.eastlink.ca [24.224.136.30]) by mx1.freebsd.org (Postfix) with ESMTP id CA4F78FC0C for ; Wed, 5 Jan 2011 15:55:12 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; CHARSET=US-ASCII Received: from ip04.eastlink.ca ([unknown] [24.222.39.52]) by mta01.eastlink.ca (Sun Java(tm) System Messaging Server 7u3-12.01 64bit (built Oct 15 2009)) with ESMTP id <0LEK00F0N47Z3S13@mta01.eastlink.ca> for freebsd-stable@freebsd.org; Wed, 05 Jan 2011 11:55:11 -0400 (AST) X-CMAE-Score: 0 X-CMAE-Analysis: v=1.1 cv=b0sI0M7bjhCmEOs51LbeKzGQ5ECIs9m+H5QCeOcUmtc= c=1 sm=1 a=tZDC3L0OECsA:10 a=kj9zAlcOel0A:10 a=6I5d2MoRAAAA:8 a=rIORHrRF1m2Q5aHVDYIA:9 a=O7Plqn6INxnUEzwNtqYA:7 a=7TZTqBoEkT9my9Q_mycHh42G1IkA:4 a=CjuIK1q_8ugA:10 a=SV7veod9ZcQA:10 a=Rb26mEfMWC2AlgGA:21 a=xT4QZSMC0MRh12XL:21 a=ZjIqTmGINkQKjhCx/60B3Q==:117 Received: from blk-222-10-85.eastlink.ca (HELO server7.acsi.ca) ([24.222.10.85]) by ip04.eastlink.ca with ESMTP; Wed, 05 Jan 2011 11:55:10 -0400 Received: from server7.acsi.ca ([192.168.9.7]) by server7.acsi.ca ([192.168.9.7]) with mapi; Wed, 05 Jan 2011 11:55:11 -0400 From: Chris Forgeron To: 'Damien Fleuriot' Date: Wed, 05 Jan 2011 11:55:10 -0400 Thread-topic: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks Thread-index: Acust0EEptjDHfiKS9Gx0g+Oy6u5TQAOGNeg Message-id: References: <4D1C6F90.3080206@my.gd> <4D21E679.80002@my.gd> <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> In-reply-to: <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> Accept-Language: en-US Content-language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Cc: "freebsd-stable@freebsd.org" Subject: RE: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Jan 2011 15:55:13 -0000 First off, raidz2 and raidz1 with copies=2 are not the same thing. raidz2 will give you two copies of parity instead of just one. It also guarantees that this parity is on different drives. You can sustain 2 drive failures without data loss. raidz1 with copies=2 will give you two copies of all your files, but there is no guarantee that they are on different drives, and you can still only sustain 1 drive failure. You'll have better space efficiency with raidz2 if you're using 9 drives. If I were you, I'd use your 9 disks as one big raidz, or better yet, get 10 disks, and make a stripe of 2 5 disk raidz's for the best performance. Save your SSD drive for the L2ARC (cache) or ZIL, you'll get better speed that way instead of throwing it away on a boot drive. -- -----Original Message----- From: owner-freebsd-stable@freebsd.org [mailto:owner-freebsd-stable@freebsd.org] On Behalf Of Damien Fleuriot Sent: January-05-11 5:01 AM To: Damien Fleuriot Cc: freebsd-stable@freebsd.org Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks Hi again List, I'm not so sure about using raidz2 anymore, I'm concerned for the performance. Basically I have 9x 1.5T sata drives. raidz2 and 2x raidz1 will provide the same capacity. Are there any cons against using 2x raidz1 instead of 1x raidz2 ? I plan on using a SSD drive for the OS, 40-64gb, with 15 for the system itself and some spare. Is it worth using the free space for cache ? ZIL ? both ? @jean-yves : didn't you experience problems recently when using both ? --- Fleuriot Damien On 3 Jan 2011, at 16:08, Damien Fleuriot wrote: > > > On 1/3/11 2:17 PM, Ivan Voras wrote: >> On 12/30/10 12:40, Damien Fleuriot wrote: >> >>> I am concerned that in the event a drive fails, I won't be able to >>> repair the disks in time before another actually fails. >> >> An old trick to avoid that is to buy drives from different series or >> manufacturers (the theory is that identical drives tend to fail at >> the same time), but this may not be applicable if you have 5 drives >> in a volume :) Still, you can try playing with RAIDZ levels and probabilities. >> > > That's sound advice, although one also hears that they should get > devices from the same vendor for maximum compatibility -.- > > > Ah well, next time ;) > > > A piece of advice I shall heed though is using 1% less capacity than > what the disks really provide, in case one day I have to swap a drive > and its replacement is a few kbytes smaller (thus preventing a rebuild). _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"