From owner-freebsd-fs@FreeBSD.ORG Wed Jun 12 23:15:05 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id 1B9E644D for ; Wed, 12 Jun 2013 23:15:05 +0000 (UTC) (envelope-from wmn@siberianet.ru) Received: from mail.siberianet.ru (mail.siberianet.ru [89.105.136.7]) by mx1.freebsd.org (Postfix) with ESMTP id BFAD619D0 for ; Wed, 12 Jun 2013 23:15:04 +0000 (UTC) Received: from book.localnet (wmn.siberianet.ru [89.105.137.12]) by mail.siberianet.ru (Postfix) with ESMTP id D4FD612FB34; Thu, 13 Jun 2013 07:05:27 +0800 (KRAT) From: Sergey Lobanov Organization: ISP "SiberiaNet" To: freebsd-fs@freebsd.org Subject: Re: An order of magnitude higher IOPS needed with ZFS than UFS Date: Thu, 13 Jun 2013 07:05:26 +0800 User-Agent: KMail/1.13.7 (FreeBSD/9.0-RELEASE-p3; KDE/4.7.3; amd64; ; ) References: <51B79023.5020109@fsn.hu> <20130612114937.GA13688@icarus.home.lan> In-Reply-To: <20130612114937.GA13688@icarus.home.lan> MIME-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Message-Id: <201306130705.26895.wmn@siberianet.ru> X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Jun 2013 23:15:05 -0000 On Wednesday 12 June 2013, Jeremy Chadwick wrote: > On Wed, Jun 12, 2013 at 06:40:32AM -0500, Mark Felder wrote: > > On Tue, 11 Jun 2013 16:01:23 -0500, Attila Nagy wrote: > > >BTW, the file systems are 77-78% full according to df (so ZFS > > >holds more, because UFS is -m 8). > > > > ZFS write performance can begin to drop pretty badly when you get > > around 80% full. I've not seen any benchmarks showing an improvement > > with a very fast and large ZIL or tons of memory, but I'd expect > > that would help significantly. Just note that you're right at the > > edge where performance gets impacted. > > Mark, do you have any references for this? I'd love to learn/read more > about this engineering/design aspect (I won't say flaw, I'll just say > aspect) to ZFS, as it's the first I've heard of it. > > The reason I ask: (respectfully, not judgementally) I'm worried you > might be referring to something that has to do with SSDs and not ZFS, > specifically SSD wear-levelling performing better with lots of free > space (i.e. a small FTL map; TRIM helps with this immensely) -- where > the performance hit tends to begin around the 70-80% mark. (I can talk > more about that if asked, but want to make sure the two things aren't > being mistaken for one another) http://lists.freebsd.org/pipermail/freebsd-fs/2013-March/016834.html CC'd mm@. -- ISP "SiberiaNet" System and Network Administrator