Re: free space is missing after dist upgrade on lzo compressed vol

[Hugo Mills <hugo@carfax.org.uk>]

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On Fri, Nov 13, 2015 at 04:33:23PM -0600, Brenton Chapin wrote:
> I was running Lubuntu 14.04 on btrfs with lzo compresssion on, with
> the following partition scheme:
> 
> sda5   232M  /boot
> sda6   16G   /
> sda7   104G /home
> 
> (sda5 is ext4)
> 
> I did 2 distribution upgrades, one after the other, to 15.04, then
> 15.10, since the upgrade utility would not go directly to the latest
> version.  This process did a whole lot of reading and writing to the
> root volume of course.  Everything seems to be working, except most of
> the free space I had on sda6 is gone.  Was using about 4G, now df
> reports that the usage is 12G.  At first, I thought Lubuntu had not
> removed old files, but I can't find anything old left behind.  I began
> to suspect btrfs, and checking, find that du shows only 4G used on
> sda6.  Where'd the other 8G go?

   Do you have snapshots? Are you running snapper, for example?

   The other place that large amounts of space can go over an upgrade
is in orphans -- files that are deleted, but still held open by
processes, and which therefore can't be reclaimed until the process is
restarted. I've been bitten by that one before.

   Hugo.

> "btrfs fi df /" reports the following:
> 
> Data, single: total=11.01GiB, used=10.58GiB
> System, DUP: total=8.00MiB, used=16.00KiB
> System, single: total=4.00MiB, used=0.00B
> Metadata, DUP: total=1.00GiB, used=397.80MiB
> Metadata, single: total=8.00MiB, used=0.00B
> GlobalReserve, single: total=144.00MiB, used=0.00B
> 
> "btrfs filesystem show /" gives:
> 
> Label: none  uuid: 4ea4ac08-ff37-4b51-b1a3-d8b21fd43ddd
>     Total devices 1 FS bytes used 10.97GiB
>     devid    1 size 15.02GiB used 13.04GiB path /dev/sda6
> 
> btrfs-progs v4.0
> 
> "du --max-depth=1 -h -x" on / shows:
> 
> 29M    ./etc
> 0    ./media
> 16M    ./bin
> 354M    ./lib
> 4.0K    ./lib64
> 0    ./mnt
> 160K    ./root
> 12M    ./sbin
> 0    ./srv
> 4.0K    ./tmp
> 3.1G    ./usr
> 442M    ./var
> 0    ./cdrom
> 3.8M    ./lib32
> 3.9G    .
> 
> And of course df:
> 
> /dev/sda6        16G   12G  2.5G  83% /
> /dev/sda5       232M   53M  163M  25% /boot
> /dev/sda7       104G   46G   57G  45% /home
> 
> And mount:
> 
> mount |grep sda
> /dev/sda6 on / type btrfs
> (rw,relatime,compress=lzo,space_cache,subvolid=257,subvol=/@)
> /dev/sda5 on /boot type ext4 (rw,relatime,data=ordered)
> /dev/sda7 on /home type btrfs
> (rw,relatime,compress=lzo,space_cache,subvolid=257,subvol=/@home)
> 
> uname -a
> Linux ichor 4.2.0-18-generic #22-Ubuntu SMP Fri Nov 6 18:25:50 UTC
> 2015 x86_64 x86_64 x86_64 GNU/Linux
> 
> I can live with the situation, but recovering that space would be nice.

-- 
Hugo Mills             | Happiness is mandatory. Are you happy?
hugo@... carfax.org.uk |
http://carfax.org.uk/  |
PGP: E2AB1DE4          |                                              Paranoia

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