On 02/04/2015 06:27 PM, Chris Murphy wrote:
On Wed, Feb 4, 2015 at 3:54 PM, Markus Moeller <hua...@moeller.plus.com> 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.
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