From owner-freebsd-stable@FreeBSD.ORG Tue Oct 14 00:08:16 2014 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 08B3FCF; Tue, 14 Oct 2014 00:08:16 +0000 (UTC) Received: from smtp1.multiplay.co.uk (smtp1.multiplay.co.uk [85.236.96.35]) by mx1.freebsd.org (Postfix) with ESMTP id C0F257E8; Tue, 14 Oct 2014 00:08:15 +0000 (UTC) Received: by smtp1.multiplay.co.uk (Postfix, from userid 65534) id 3D53420E7090C; Tue, 14 Oct 2014 00:08:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.multiplay.co.uk X-Spam-Level: ** X-Spam-Status: No, score=2.2 required=8.0 tests=AWL,BAYES_00,DOS_OE_TO_MX, FSL_HELO_NON_FQDN_1,RDNS_DYNAMIC,STOX_REPLY_TYPE autolearn=no version=3.3.1 Received: from r2d2 (82-69-141-170.dsl.in-addr.zen.co.uk [82.69.141.170]) by smtp1.multiplay.co.uk (Postfix) with ESMTPS id 30AC720E70908; Tue, 14 Oct 2014 00:08:11 +0000 (UTC) Message-ID: <3E07EBCFC6914F9D8BF582DDA08F360D@multiplay.co.uk> From: "Steven Hartland" To: "Ben Morrow" , , References: <77AA5757-5DC1-415B-899E-30545BF91516@mac.com> <20141013235951.GA43024@anubis.morrow.me.uk> Subject: Re: getting to 4K disk blocks in ZFS Date: Tue, 14 Oct 2014 01:08:08 +0100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 14 Oct 2014 00:08:16 -0000 ----- Original Message ----- From: "Ben Morrow" > Put a UFS on a zvol? You get the raidz/snapshots of the zpool but since > UFS uses fragments you should waste less space with small files. So your forcing to do exactly what it did when using 512b sectors just with an extra layer in the middle for no reason. Doesn't sound like a good idea. > In principle ZFS could use fragments too, though the copy-on-write logic > would end up looking exactly like SSD wear-levelling logic, and might be > slow enough to be a problem. I don't know if anyone is working on this. Most SSD's advertise this so you could achieve this if you wanted to but then your just back where you started from. Regards Steve