From owner-freebsd-virtualization@freebsd.org Tue Aug 7 18:57:22 2018 Return-Path: Delivered-To: freebsd-virtualization@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 32AA41067D04 for ; Tue, 7 Aug 2018 18:57:22 +0000 (UTC) (envelope-from hicks@cgi.cz) Received: from hel.cgi.cz (hel.cgi.cz [178.238.36.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 9B0997C662 for ; Tue, 7 Aug 2018 18:57:21 +0000 (UTC) (envelope-from hicks@cgi.cz) Received: from hel.cgi.cz (localhost [127.0.0.1]) by hel.cgi.cz (Postfix) with ESMTP id B371B130E9B for ; Tue, 7 Aug 2018 20:57:12 +0200 (CEST) X-Virus-Scanned: amavisd-new at cgi.cz Received: from hel.cgi.cz ([127.0.0.1]) by hel.cgi.cz (hel.cgi.cz [127.0.0.1]) (amavisd-new, port 10024) with LMTP id j8DsJed0vTpt for ; Tue, 7 Aug 2018 20:57:10 +0200 (CEST) Received: from mail2.cgi.cz (hermes [172.17.174.1]) (using TLSv1 with cipher ADH-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by hel.cgi.cz (Postfix) with ESMTPS id 1DF33130E7D for ; Tue, 7 Aug 2018 20:57:10 +0200 (CEST) Received: from [192.168.8.106] (unknown [82.100.31.11]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by mail2.cgi.cz (Postfix) with ESMTPSA id EF6465B4BE for ; Tue, 7 Aug 2018 20:57:09 +0200 (CEST) Subject: Re: Seeking advice on virtualization To: freebsd-virtualization@freebsd.org References: <20180805224205.GB17784@tau1.ceti.pl> <20180807170648.GA1599@tau1.ceti.pl> From: Jakub Chromy Message-ID: Date: Tue, 7 Aug 2018 20:57:10 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20180807170648.GA1599@tau1.ceti.pl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-GB X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Aug 2018 18:57:22 -0000 > I was writing about "hard disk file" format, in which a hypervisor > (i.e. bhyve, kvm, virtualbox) is keeping a disk for emulated > machine. Wikipedia calls it "img format": > > https://en.wikipedia.org/wiki/IMG_(file_format) > > Advantage from using this format (as opposed to something like qcow or > vmhd) is that, in theory (and even in practice) one can boot such > machine (I mean, virtual machine defined with such "raw" hard drives) > using any hypervisor. ZFS ZVOL is a true "raw device" as well... (or at least it did behave like that for me):   dd if=/dev/zvol/pool/mypornhubpremiumarchive0 of=/var/vm/mypornhubpremiumarchive0.raw but you get snapshots, zfs send | zfs recv and stuff. -- regards / s pozdravem Jakub Chromy CGI Systems div. ---------------- CGI CZ s.r.o. sales@cgi.cz 775 144 257 234 697 102 www.cgi.cz On 7.8.2018 19:06, Tomasz Rola wrote: > On Mon, Aug 06, 2018 at 12:07:13AM +0100, Paul Webster wrote: >> In theory as ZFS works on both linux and BSD you could simply use vdevs and >> snapshots for easy transport > Um-hm. > > I was writing about "hard disk file" format, in which a hypervisor > (i.e. bhyve, kvm, virtualbox) is keeping a disk for emulated > machine. Wikipedia calls it "img format": > > https://en.wikipedia.org/wiki/IMG_(file_format) > > Advantage from using this format (as opposed to something like qcow or > vmhd) is that, in theory (and even in practice) one can boot such > machine (I mean, virtual machine defined with such "raw" hard drives) > using any hypervisor. Or to put it differently, it is not proprietary > and is the easiest one to implement, so it is what most probably will > keep being used years or decades from now (in whatever hypervisor / PC > emulator of the future day is fashionable). > > I believe in the past I have installed an OS (say, FreeDOS) using > virtualbox and after deciding I would not use virtualbox in a future, > I started to boot said machine using kvm. Likewise, I believe some > OSes rejected being installed under certain hypervisor, so one had to > install them using this other hypervisor and then could happily > continue to run it under his preferred hypervisor. > > All of this made possible thanks to avoiding file formats supported by > one or only few hypervisors. > > Of course there are many hd-file formats and some are supported by > more than one hypervisor, but the easiest one is raw and in case of > emergency it can be also mounted as any other block device (always, I > guess, but I would pay attention to block size mismatch). >