From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f171.google.com ([209.85.223.171]:38085 "EHLO mail-io0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751289AbdILLS2 (ORCPT ); Tue, 12 Sep 2017 07:18:28 -0400 Received: by mail-io0-f171.google.com with SMTP id n69so43540236ioi.5 for ; Tue, 12 Sep 2017 04:18:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20170912111159.jcwej7s6uluz4dsz@angband.pl> References: <2ee9f15b-a11a-886e-2460-557bb9f8d41d@rqc.ru> <69e843f4-1233-261a-3b88-306359ef20c9@rqc.ru> <20170912103214.6dzjlugcr7q47x6g@angband.pl> <2a0186c7-7c56-2132-fa0d-da2129cde22c@rqc.ru> <20170912111159.jcwej7s6uluz4dsz@angband.pl> From: Timofey Titovets Date: Tue, 12 Sep 2017 14:17:47 +0300 Message-ID: Subject: Re: qemu-kvm VM died during partial raid1 problems of btrfs To: Adam Borowski Cc: Marat Khalili , Duncan <1i5t5.duncan@cox.net>, linux-btrfs Content-Type: text/plain; charset="UTF-8" Sender: linux-btrfs-owner@vger.kernel.org List-ID: 2017-09-12 14:12 GMT+03:00 Adam Borowski : > On Tue, Sep 12, 2017 at 02:01:53PM +0300, Timofey Titovets wrote: >> > On 12/09/17 13:32, Adam Borowski wrote: >> >> Just use raw -- btrfs already has every feature that qcow2 has, and >> >> does it better. This doesn't mean btrfs is the best choice for hosting >> >> VM files, just that raw-over-btrfs is strictly better than >> >> qcow2-over-btrfs. >> > >> > Thanks for advice, I wasn't sure I won't lose features, and was too lazy to >> > investigate/ask. Now it looks simple. >> >> The main problem with Raw over Btrfs is that (IIRC) no one support >> btrfs features. >> >> - Patches for libvirt not merged and obsolete >> - Patches for Proxmox also not merged >> - Other VM hypervisor like Virtualbox, VMware just ignore btrfs features. >> >> So with raw you will have a problems like: no snapshot support > > Why would you need support in the hypervisor if cp --reflink=always is > enough? Likewise, I wouldn't expect hypervisors to implement support for > every dedup tool -- it'd be a layering violation[1]. It's not emacs or > systemd, you really can use an external tool instead of adding a lawnmower > to the kitchen sink. > > > Meow! > > [1] Yeah, talking about layering violations in btrfs context is a bit weird, > but it's better to at least try. In that case why Hypervisors add support for LVM snapshots, ZFS, RBD Snapshot & etc? User can do that by hand, so it's useless, nope? (rhetorical question) This is not about layering violation with about teaming and integration between tools. -- Have a nice day, Timofey.