Arch Linux

Ichirou

Member

Registered: 2020-02-11

Posts: 14

[Solved] Problem in free space displaying

I just created a new partition for my virtual machine (KVM) which is /dev/sda1. After that I noticed my root partition (/dev/sdb8) usage percentage just went up straight to 99%. I don't think those 2 are related to each other but that's the only thing I can think of right now. So I tried df, ncdu and display from filesystem module of polybar (which displayed root as 99%). Here are the other 2's outputs (all executed as root)
> df -h

Filesystem      Size  Used Avail Use% Mounted on
dev             7.8G     0  7.8G   0% /dev
run             7.8G  1.1M  7.8G   1% /run
/dev/sdb8        59G   56G  613M  99% /
tmpfs           7.8G   73M  7.8G   1% /dev/shm
tmpfs           7.8G     0  7.8G   0% /sys/fs/cgroup
tmpfs           7.8G   12K  7.8G   1% /tmp
/dev/sdb9        92G   42G   46G  48% /media/ichirou2910/vm
/dev/sdb6       488M   57M  396M  13% /boot
/dev/sdb2        95M  2.8M   93M   3% /efi
/dev/sda1       393G   73M  373G   1% /media/ichirou2910/vm-data
/dev/sda6       246G  166G   67G  72% /home
tmpfs           1.6G  8.0K  1.6G   1% /run/user/1000

> ncdu -x /

    7.2 GiB [##########] /usr
    4.4 GiB [######    ] /var
  413.3 MiB [          ] /opt
    8.8 MiB [          ] /etc
    3.5 MiB [          ] /root
   20.0 KiB [          ] /media
e  16.0 KiB [          ] /lost+found
   12.0 KiB [          ] /srv
    8.0 KiB [          ] /mnt
@   0.0   B [          ]  sbin
@   0.0   B [          ]  lib64
@   0.0   B [          ]  lib
@   0.0   B [          ]  bin
>   0.0   B [          ] /tmp
>   0.0   B [          ] /sys
>   0.0   B [          ] /run
>   0.0   B [          ] /proc
>   0.0   B [          ] /home
>   0.0   B [          ] /efi
>   0.0   B [          ] /dev
>   0.0   B [          ] /boot
 Total disk usage:  12.0 GiB  Apparent size:  12.0 GiB  Items: 191254

As you can see, df gave out different output from ncdu. I'm pretty sure ncdu's output is correct, rather than df's. I booted into arch installation media and tried running df, it gave out the same output, and fsck returned no error.
I don't know what is happening right now. Any help is appreciated.

Last edited by Ichirou (2020-02-12 15:24:37)

frostschutz

Member

Registered: 2013-11-15

Posts: 1,657

Re: [Solved] Problem in free space displaying

try without -x to look for files hidden beneath other mountpoints

mkdir /mnt/root
mount --bind / /mnt/root
ncdu /mnt/root

otherwise it could be deleted files (lsof) but in that case it'd be gone after reboot

then there's a possibility of filesystem inconsistency or bug, I think btrfs had such an issue very recently

Ichirou

Member

Registered: 2020-02-11

Posts: 14

Re: [Solved] Problem in free space displaying

Thanks for your help. There are indeed hidden files
> ncdu /mnt/root

--- /mnt/root ------------------------------------------------------------------------------------------------
   43.2 GiB [##########] /media
    7.2 GiB [#         ] /usr
    4.4 GiB [#         ] /var
  413.3 MiB [          ] /opt
    8.8 MiB [          ] /etc
    3.5 MiB [          ] /root
e  16.0 KiB [          ] /lost+found
   12.0 KiB [          ] /srv
   12.0 KiB [          ] /mnt
e   4.0 KiB [          ] /tmp
e   4.0 KiB [          ] /sys
e   4.0 KiB [          ] /run
e   4.0 KiB [          ] /proc
e   4.0 KiB [          ] /home
e   4.0 KiB [          ] /efi
e   4.0 KiB [          ] /dev
e   4.0 KiB [          ] /boot
@   0.0   B [          ]  sbin
@   0.0   B [          ]  lib64
@   0.0   B [          ]  lib
@   0.0   B [          ]  bin
 Total disk usage:  55.1 GiB  Apparent size: 112.0 GiB  Items: 191256

The large size is from my newly created partition, which is mounted to /media/ichirou2910/vm-data
But then that's weird. I created 2 different partitions and mounted them on vm-data and vm by fstab, but how come only the one (created today) got counted in root partition size? Do you have any idea?

--- /mnt/root/media/ichirou2910 ------------------------------------------------------------------------------
                         /..
   43.2 GiB [##########] /vm-data
e   4.0 KiB [          ] /vm
e   4.0 KiB [          ] /aq
 Total disk usage:  43.2 GiB  Apparent size: 100.0 GiB  Items: 4

> cat /etc/fstab

# Static information about the filesystems.
# See fstab(5) for details.

# <file system> <dir> <type> <options> <dump> <pass>
# /dev/sdb8
UUID=8bb10fcc-7bda-44f4-8e49-784141052eda	/         	ext4      	rw,relatime	0 1

# /dev/sdb6
UUID=3aeb96e8-16cd-4104-bd7d-cf3556ad8603	/boot     	ext4      	rw,relatime	0 2

# /dev/sda6
UUID=06d6ca63-ebf5-4555-b358-755fc8e7845c	/home     	ext4      	rw,relatime	0 2

# /dev/sdb2
UUID=F4CE-0820      	/efi      	vfat      	rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro	0 2

# /dev/sdb7
UUID=64f3207c-1044-4389-a76a-90fc4dc39c06	none      	swap      	defaults  	0 0

# /dev/sdb9
UUID=dcc72e71-a5c0-4106-bf2c-29c175d1f7c8	/media/ichirou2910/vm    ext4    nofail,user,relatime 0 2

# /dev/sda1
UUID=3d8b76f1-9cb2-4928-8c51-a1fae0c3866e	/media/ichirou2910/vm-data	ext4	nofail,user,relatime 0 2

Ichirou

Member

Registered: 2020-02-11

Posts: 14

Re: [Solved] Problem in free space displaying

I want to give out more information as things are getting confusing for me. I used ranger to explore /media from /root and from binded /root but they gave out different results
https://imgur.com/MjJp7Do
I don't know why, tbh

frostschutz

Member

Registered: 2013-11-15

Posts: 1,657

Re: [Solved] Problem in free space displaying

it's a common user error, to place files in a mount directory, when the filesystem wasn't mounted yet so those files really end up on /

whether those files are important or need to be kept or can be deleted, only you can figure out... check lsof, and file timestamps, perhaps...?

if unsure, move the files to another disk instead of deleting them