From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from resqmta-po-11v.sys.comcast.net ([96.114.154.170]:32930 "EHLO resqmta-po-11v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751260AbbBEDsn (ORCPT ); Wed, 4 Feb 2015 22:48:43 -0500 Message-ID: <54D2E62E.7080208@pobox.com> Date: Wed, 04 Feb 2015 19:40:30 -0800 From: Robert White MIME-Version: 1.0 To: Chris Murphy , Markus Moeller CC: Btrfs BTRFS Subject: Re: Btrfs subvolume question References: In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 02/04/2015 06:27 PM, Chris Murphy wrote: > On Wed, Feb 4, 2015 at 3:54 PM, Markus Moeller wrote: >> Hi , >> >> I am new to btrfs and wonder what I need to do to move subvolumes to the >> right filesystem. I see the following: >> >> df -h >> Filesystem Size Used Avail Use% Mounted on >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% / >> devtmpfs 235M 8.0K 235M 1% /dev >> tmpfs 242M 84K 242M 1% /dev/shm >> tmpfs 242M 2.4M 240M 1% /run >> tmpfs 242M 0 242M 0% /sys/fs/cgroup >> /dev/mapper/system_13.2-usr_lv 18G 6.9G 10G 41% /usr >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /srv >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /.snapshots >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /tmp >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /usr/local >> /dev/sda2 486M 59M 398M 13% /boot >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% >> /boot/grub2/x86_64-efi >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /boot/grub2/i386-pc >> /dev/mapper/export_vg-export_lv 20G 18G 2.9G 86% /export >> /dev/mapper/export_vg-src_lv 5.0G 2.6G 2.5G 51% /src >> /dev/mapper/system_13.2-var_lv 4.0G 196M 3.4G 6% /var >> /dev/mapper/system_13.2-opt_lv 6.0G 152M 5.3G 3% /opt >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/spool >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/tmp >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/opt >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/log >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/lib/named >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/lib/mailman >> /dev/mapper/system_13.2-root_lv 5.0G 1.5G 3.2G 32% /var/lib/pgsql >> >> >> and I would like to have all the var subvolumes using the /var filesystem >> space and not root. The same for /boot/grub2 subvolumes. They should use >> the /boot filesystem. > > The giveaway is in the first column. All of these are device mapper > LVM LV's, they are not Btrfs subvolumes, in fact they're separate > Btrfs volumes (unique, unrelated filesystems). What's suspicious, > though, is that a bunch of these LV's have exactly 1.5G Used, which > makes no sense. For example, /boot/grub2/i386-pc has 1.5G used, but > that's not possible, the entire GRUB2 package is maybe 50MB. Actually given that the first column repeats /dev/mapper/system_13.2-root_lv as the device, I think he's repeatedly mounted the same device filesystem with different subovol= directives. That's why so many of them have the same 1.5G used. In terms of actual LVs he only seems to have _root_ _opt_ _var_ and _usr_ once you strip away the various noise components. In particular oddity fassion /var is a different device but /var/log goes back to the root device. In a slightly over-thought way its kind of twisted genius if you view /var/lib/named and such as being tightly bound to /etc. (/var/tmp is totally wrong.) It's not something I would want to maintain either. They also might be bind mounts instead of subvol= mounts. I'd have to see /etc/fstab. The output of btrfs subvol list on / /var /usr and /opt would be nice as well. > > Honestly, I suggest reinstalling and don't deal with the tricky task > of converting all of this. It'll take longer for me to explain, and > you to read, how to fix this without reinstalling. I also suggest > making sure that you don't put Btrfs on LVM, there's no good reason to > do this for most use cases. > > > I don't know how I got to this and don't know how to >> change. > > It's not your fault. This is a pathological side effect of openSUSE > 13.2's, quite frankly bizarre, layout. By default it creates a single > Btrfs volume, and makes all of these subvolumes, which is strange > enough on its own because it's overly complicated (just look at > /etc/fstab) for no good reason. But somehow in your case, you ended up > with a bunch of LVM LVs first, and then each of those is a Btrfs > volume. If it were me, I'd file a bug report against 13.2, and then > file a feature request citing the bug report. If you don't want to do > both, then just file the feature request against Factory because > installer related bug reports on openSUSE basically get rejected > seeing as there's nothing that can be done about it in Distribution > now anyway. >