From owner-freebsd-questions@freebsd.org Thu Aug 31 14:26:24 2017 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E670FE1FB1D for ; Thu, 31 Aug 2017 14:26:24 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from bs1.fjl.org.uk (bs1.fjl.org.uk [84.45.41.196]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "bs1.fjl.org.uk", Issuer "bs1.fjl.org.uk" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 9A8787E355 for ; Thu, 31 Aug 2017 14:26:23 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from [10.4.242.25] ([46.233.78.25]) (authenticated bits=0) by bs1.fjl.org.uk (8.14.4/8.14.4) with ESMTP id v7VEQJga006533 (version=TLSv1/SSLv3 cipher=DHE-DSS-AES128-SHA bits=128 verify=NO) for ; Thu, 31 Aug 2017 15:26:21 +0100 (BST) (envelope-from frank2@fjl.co.uk) Message-ID: <59A81C8F.9020002@fjl.co.uk> Date: Thu, 31 Aug 2017 15:26:23 +0100 From: Frank Leonhardt Reply-To: frank2@fjl.co.uk Organization: Frank Leonhardt User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: freebsd-questions@freebsd.org Subject: Re: help creating new gmirror > 2TB References: <26f5e88e-1ea7-6332-ca5e-f055cfbdd280@fjl.co.uk> In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 31 Aug 2017 14:26:25 -0000 On 31/08/2017 01:59, Warren Block wrote: > On Wed, 30 Aug 2017, Frank Leonhardt wrote: >> Trying to get geom mirror to work with GPT as it stands just leads to >> pain. I've taken a look at the code with a view to fixing this is no >> one else does, but UFS is so un-cool in most circles and I don't >> fancy doing it alone in case I zap someone's data. it doesn't look >> that tricky to move the metadata somewhere else, and by checking for >> a GPT you can select between the old/new block. It's unexpected >> interactions I'm worried about. > > At some point in the last couple of years, hrs@ produced a working > patch which did something like that, although I don't remember the > details. It moved either the GPT backup table or the gmirror > metadata. It was turned down as breaking standards. I remember something like this too - if you turn it up please point me at it! I have a feeling that it moved the GPT backup for some reason. Moving the mirror metadata would make more sense, but I assume this was tricky for some reason. I think there's a good argument for a geom mirror2, designed to work with GPT. IME ZFS isn't the universal answer to everything thanks to CoW, random-access R/W files and fragmentation. Until the fragmentation issue can be addressed (e.g. with a defragger) databases and VM images are going to run badly. Another answer would be for a FS to access it at vdev level (i.e. just use the volume manager aspect). At the moment it's a CoW dataset or a CoW dataset. I'd assumed Oracle would have addressed this, given their interest in databases. Regards, Frank.