From owner-freebsd-fs@FreeBSD.ORG Tue Aug 28 18:50:21 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 34AC81065706 for ; Tue, 28 Aug 2012 18:50:21 +0000 (UTC) (envelope-from mailinglists@nobaq.net) Received: from mail.nobaq.net (mail.nobaq.net [IPv6:2001:7b8:3cd:3::172]) by mx1.freebsd.org (Postfix) with ESMTP id B4D768FC17 for ; Tue, 28 Aug 2012 18:50:20 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=mail.nobaq.net) by mail.nobaq.net with esmtp (Exim 4.72) (envelope-from ) id 1T6Qrh-0005lP-BB; Tue, 28 Aug 2012 20:50:18 +0200 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=nobaq.net; h=message-id :date:from:mime-version:to:cc:references:in-reply-to :content-type:content-transfer-encoding:subject; s=n200908; bh=p JvcHHhDeiX/P8+cLCQx011Qyok=; b=ZMDdLxQo27ydrbwfE01KQ6xGp9uPQ4Kyv bLzteupEI1OpOmHk3bIy5PhqtSdJKQAUzXVr2wJ+kWYOGoo1nSv/HoT/PNxLElGA mZVe8RjlgnMBuU1EYfPnTAmF5yM1OSBA+w2vz7SgIz8X81fTHkqVdVFtI9etqTLF Eh/CTegxA8= DomainKey-Signature: a=rsa-sha1; c=nofws; d=nobaq.net; h=message-id:date :from:mime-version:to:cc:references:in-reply-to:content-type :content-transfer-encoding:subject; q=dns; s=n200908; b=Gm2zNgDm cfOI0JJ1kVHTOziKffuqRDc1rDM5Ulh16f+d8aeaGsHyx3XGxSTnW/vB3hdvmeLn mxFl+z/eItx8upvkDpqTO+OfsjwqqyiU1x0GXZ/6TKdxvap7b9bAuVPL/FhFcqtw 63tEjZLW9+oY0JR5vEb9qxQRRJ60c7ZXRaU= Received: from gate.nobaq.net ([93.83.102.170] helo=[192.168.200.202]) by mail.nobaq.net with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from ) id 1T6QrO-0005lF-Qc; Tue, 28 Aug 2012 20:50:16 +0200 Message-ID: <503D12DB.3040909@nobaq.net> Date: Tue, 28 Aug 2012 20:50:03 +0200 From: Niki Hammler User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.1.24) Gecko/20100228 Thunderbird/2.0.0.24 Mnenhy/0.7.5.0 MIME-Version: 1.0 To: Freddie Cash References: <503A6F9F.7070801@nobaq.net> <503C8AEE.1090703@nobaq.net> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.nobaq.net X-Spam-Level: X-Spam-Status: No, score=-3.1 required=5.0 tests=ALL_TRUSTED,BAYES_00, RP_MATCHES_RCVD autolearn=ham version=3.3.1 X-SA-Exim-Connect-IP: 127.0.0.1 X-SA-Exim-Mail-From: mailinglists@nobaq.net X-SA-Exim-Scanned: No (on mail.nobaq.net); SAEximRunCond expanded to false Cc: freebsd-fs@freebsd.org Subject: Re: zvol + raidz issue? X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Aug 2012 18:50:21 -0000 Am 28.08.2012 17:27, schrieb Freddie Cash: > On Tue, Aug 28, 2012 at 2:10 AM, Niki Hammler wrote: >> Am 26.08.2012 22:13, schrieb Freddie Cash: >>> (Sorry for top-post, sending from phone.) >>> >>> Please show the command-line used to create the zvol. Especially the >>> recordsize option. When using zvols, you have to make sure to match the >>> recordsize of the zvol to that of the filesystem used above it. >>> Otherwise, performance will be atrocious. >> >> Sorry for my third posting on this. >> Now I strictly followed your suggestion and used >> >> zfs create -b 128k -V 500g plvl5i0/zvtest >> >> (with 128k being the recordsize of the dataset in the zpool). >> >> Suddenly the write performance increased from the 2.5 MB/s to 250 MB/s >> (or 78MB/s when using bs=4096 with dd) >> >> 1.) How can this explained? >> 2.) Is there any problem when choosing -b 128k (can I always blindly >> choose -b 128k)? >> >> Remember again that the problem ONLY occurs with raidz1+zvol+force 4096 >> block alignment and in no other case! > > Most likely it has to do with the raidz stripe size and the constant > block size of the zvol causing alignment or similar issues. Yes, but I thought a zvol is merely a file in a zpool? How can it be explained that writing to a file (with the same parameters!) is OK while writing to a zvol drastically slower? Is there anything I can check/debug? I already filed a bug in FreeNAS but since this seems to be FreeBSD-related I will also file a bug report for FreeBSD. > I've also seen indications in the zfs-discuss mailing list about > optimal and sub-optimal disk configurations for the various raidz > types (wrong number of disks in the vdev leads to horrible > performance). Yes, I know this. In my case it's 3x2TB which is fine. Regards, Niki