From owner-freebsd-stable@FreeBSD.ORG Thu Jan 6 11:26:35 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 EEE6F106566B for ; Thu, 6 Jan 2011 11:26:35 +0000 (UTC) (envelope-from cforgeron@acsi.ca) Received: from mta03.eastlink.ca (mta03.eastlink.ca [24.224.136.9]) by mx1.freebsd.org (Postfix) with ESMTP id AE3198FC26 for ; Thu, 6 Jan 2011 11:26:35 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; CHARSET=US-ASCII Received: from ip05.eastlink.ca ([unknown] [24.222.39.68]) by mta03.eastlink.ca (Sun Java(tm) System Messaging Server 7.3-11.01 64bit (built Sep 1 2009)) with ESMTP id <0LEL007X5MGACF02@mta03.eastlink.ca> for freebsd-stable@freebsd.org; Thu, 06 Jan 2011 07:26:34 -0400 (AST) X-CMAE-Score: 0 X-CMAE-Analysis: v=1.1 cv=8reSTVRqS4Rq5Xx4Jai9N41eZpHz3D5gSX5rA0od4mg= c=1 sm=1 a=tZDC3L0OECsA:10 a=kj9zAlcOel0A:10 a=6I5d2MoRAAAA:8 a=T1nuC21ZD-St4ExDUygA:9 a=IoEjELlaKcY4AH21wZ8A:7 a=4QatThj9dcmXS8ILLZVmoNZcXjUA:4 a=CjuIK1q_8ugA:10 a=SV7veod9ZcQA:10 a=/bLbuBD0lrv91xL1PDQKaA==:117 Received: from blk-222-10-85.eastlink.ca (HELO server7.acsi.ca) ([24.222.10.85]) by ip05.eastlink.ca with ESMTP; Thu, 06 Jan 2011 07:26:34 -0400 Received: from server7.acsi.ca ([192.168.9.7]) by server7.acsi.ca ([192.168.9.7]) with mapi; Thu, 06 Jan 2011 07:26:34 -0400 From: Chris Forgeron To: Damien Fleuriot , Artem Belevich Date: Thu, 06 Jan 2011 07:26:32 -0400 Thread-topic: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks Thread-index: AcutgwmStifwwHkTT2GLMQ23IwicogAETuug Message-id: References: <4D1C6F90.3080206@my.gd> <4D21E679.80002@my.gd> <84882169-0461-480F-8B4C-58E794BCC8E6@my.gd> <488AE93A-97B9-4F01-AD0A-0098E4B329C3@my.gd> In-reply-to: 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: Thu, 06 Jan 2011 11:26:36 -0000 You know, these days I'm not as happy with SSD's for ZIL. I may blog about some of the speed results I've been getting over the last 6mo-1yr that I've been running them with ZFS. I think people should be using hardware RAM drives. You can get old Gigabyte i-RAM drives with 4 gig of memory for the cost of a 60 gig SSD, and it will trounce the SSD for speed. I'd put your SSD to L2ARC (cache). -----Original Message----- From: Damien Fleuriot [mailto:ml@my.gd] Sent: Thursday, January 06, 2011 5:20 AM To: Artem Belevich Cc: Chris Forgeron; freebsd-stable@freebsd.org Subject: Re: ZFS - moving from a zraid1 to zraid2 pool with 1.5tb disks You both make good points, thanks for the feedback :) I am more concerned about data protection than performance, so I suppose raidz2 is the best choice I have with such a small scale setup. Now the question that remains is wether or not to use parts of the OS's ssd for zil, cache, or both ? --- Fleuriot Damien On 5 Jan 2011, at 23:12, Artem Belevich wrote: > On Wed, Jan 5, 2011 at 1:55 PM, Damien Fleuriot wrote: >> Well actually... >> >> raidz2: >> - 7x 1.5 tb = 10.5tb >> - 2 parity drives >> >> raidz1: >> - 3x 1.5 tb = 4.5 tb >> - 4x 1.5 tb = 6 tb , total 10.5tb >> - 2 parity drives in split thus different raidz1 arrays >> >> So really, in both cases 2 different parity drives and same storage... > > In second case you get better performance, but lose some data > protection. It's still raidz1 and you can't guarantee functionality in > all cases of two drives failing. If two drives fail in the same vdev, > your entire pool will be gone. Granted, it's better than single-vdev > raidz1, but it's *not* as good as raidz2. > > --Artem