From owner-freebsd-hackers@FreeBSD.ORG Wed Jan 23 21:53:58 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 2989BDBD for ; Wed, 23 Jan 2013 21:53:58 +0000 (UTC) (envelope-from utisoft@gmail.com) Received: from mail-ie0-f179.google.com (mail-ie0-f179.google.com [209.85.223.179]) by mx1.freebsd.org (Postfix) with ESMTP id EE66E25B for ; Wed, 23 Jan 2013 21:53:57 +0000 (UTC) Received: by mail-ie0-f179.google.com with SMTP id k14so14401536iea.38 for ; Wed, 23 Jan 2013 13:53:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:mime-version:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=TCi2TIgpprzb6yn/frdpJfCPM7eAnbwirxbPdf+6fDI=; b=KK2MdJ+jDdgRfOYN4vQ74tvmhQSA8a/tNAFVK2ayEtBi8jNAzeysEdaju3huEa9m/L zmyWHDtBzgZVUQ4x6SCMGAxjlI8y3KEzGmTC3WRTC6XuuIMjppdKTxRfqpMe8NMPC1FA pmE8put5FS+xvqf7u+Ye7iHMfy5XYP5Qak3d9rYmQqgOkQhYEKCPBciE5wEuJDzkZ1AS LA4PbgInCVphXVFHmffMBxR6+ILUMcVUal/f2JkRPfz/6v8jTrxMkcOkyGfLAox1N4mI pbPo8/fQl/QIKwEvbosmja+AGdpy1UiSP0R58rEgf3tPszDF12T3lJW/iVFjr7g3fROo 3WNQ== X-Received: by 10.42.92.72 with SMTP id s8mr2204154icm.0.1358978037559; Wed, 23 Jan 2013 13:53:57 -0800 (PST) MIME-Version: 1.0 Received: by 10.64.16.73 with HTTP; Wed, 23 Jan 2013 13:53:27 -0800 (PST) In-Reply-To: <101D6382-BF57-43EB-A5FA-A63D4062F5FD@lpthe.jussieu.fr> References: <101D6382-BF57-43EB-A5FA-A63D4062F5FD@lpthe.jussieu.fr> From: Chris Rees Date: Wed, 23 Jan 2013 21:53:27 +0000 Message-ID: Subject: Re: ZFS regimen: scrub, scrub, scrub and scrub again. To: Michel Talon Content-Type: text/plain; charset=ISO-8859-1 Cc: "freebsd-hackers@freebsd.org" , Mark Felder X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Jan 2013 21:53:58 -0000 On 23 Jan 2013 21:45, "Michel Talon" wrote: > > On Wed, 23 Jan 2013 14:26:43 -0600, Chris Rees wrote: > > > > > So we have to take your word for it? > > Provide a link if you're going to make assertions, or they're no more > > than > > your own opinion. > > I've heard this same thing -- every vdev == 1 drive in performance. I've > never seen any proof/papers on it though. > > > first google answer from request "raids performance" > https://blogs.oracle.com/roch/entry/when_to_and_not_to > > Effectively, as a first approximation, an N-disk RAID-Z group will > behave as a single device in terms of delivered random input > IOPS. Thus a 10-disk group of devices each capable of 200-IOPS, will > globally act as a 200-IOPS capable RAID-Z group. This is the price to > pay to achieve proper data protection without the 2X block overhead > associated with mirroring. Thanks for the link, but I could have done that; I am attempting to explain to Wojciech that his habit of making bold assertions and arrogantly refusing to back them up makes for frustrating reading. Chris