20.04 Lack of space on Root

[Robbyx]

The user interface of disk usage analyser isn't very intuitive to everybody, but maybe it is to you.

If disk usage analyser doesn't see the files using taking all the disk space, there are several possibilities:
- Maybe some files are in directories only readable by root and disk usage analyser has no root privileges;
- Maybe there are files in a directory used as a mountpoint;
- There may be big files that are still open, but deleted. The disk space will be reclaimed when the file is closed;
- Some advanced filesystems, like btrfs, which you use, confuse the simple tools.

My guess is that your problem is specific to btrfs, but I've got no experience with that.

I have just run the following. It seems to imply that there is no fault with the btrfs root drive:

sudo btrfs scrub start -Bd  /mnt
scrub device /dev/nvme0n1p1 (id 1) done
Scrub started:    Sun Jan 10 14:21:02 2021
Status:           finished
Duration:         0:00:24
Total to scrub:   32.56GiB
Rate:             1.26GiB/s
Error summary:    no errors found

[Robbyx]

As I have run out of ideas, do you have any other suggestions to find what is taking up so much room on my root disk?

[agvantibo]

Previously people spoke just about diagnostics and never about treatment. I will solve that.

Here are the things you might want to do:

#!/bin/bash
# !!SHOULD BE RUN AS ROOT!!

# Try to remove unused dependencies
apt autoremove
# Clears apt caches
apt clean
# Optimizes stuff
apt autoclean

# Destroy old snaps
set -eu
snap list --all | awk '/disabled/{print $1, $3}' |
    while read snapname revision; do
        sudo snap remove "$snapname" --revision="$revision"
    done

# Clean archived log
rm -fvr /var/log/*gz

# Permanently reduce log size to: (5G, 1G, 500M, 1K for example)
echo 'Enter size to permanently reduce the log to (5G, 1G, 500M, 1K for example)'
read LOGSIZE
journalctl --vacuum-size=$LOGSIZE

echo Done.

Please read before copy/pasting. Use https://explainshell.com and `man` to determine command usage. Hope I'm helpful

[tea for one]

I am getting a low space message for the root (/) and would like help to find what is filling up the partiton:

According to pcmanf ,a file manager, the root has used 32.6gb and there is only 683 mb free. I have tried to find out what is making up the 32.6gb and I can only find the 11.5gb used as shown by the disk usage analyser.

There is therefore a mismatch of 21.1gb.

The /home is on a separate partition and uses 28.2gb with 41.6gb free, but the home is not part of the / directory.

blkid shows this extracted portion:

I am asking for help to find the cause of the very low free space on the root so that I can delete some files. The disprepancy is after running bleachbit.

This does seem to be a baffling question at the moment, nevertheless there must be a clue somewhere?

Which version and flavour of Ubuntu are you using?
What are you trying to do when the low space message appears?
I'm not familiar with bleachbit, is it a reliable utility?
Possibly, the file manager is reporting incorrectly due to an unknown reason?

Can you post the output from:-

df -t btrfs

[tea for one]

It seems that btrfs uses different commands to examine the file system.

I wonder if this link can provide any clues?

https://ohthehugemanatee.org/blog/20...ency-response/

[Robbyx]

This does seem to be a baffling question at the moment, nevertheless there must be a clue somewhere?

Which version and flavour of Ubuntu are you using?
What are you trying to do when the low space message appears?
I'm not familiar with bleachbit, is it a reliable utility?
Possibly, the file manager is reporting incorrectly due to an unknown reason?

Can you post the output from:-

df -t btrfs

I am using Ubuntu gnome 20.04
Bleachbit is a top rated cleanup utility.

robins@robins-desktop:~$ df -t btrfs
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/nvme0n1p1 34179072 30976360 1774344 95% /
/dev/nvme0n1p2 73242624 28273672 44205288 40% /home
/dev/nvme0n1p4 718979072 532117856 186936112 75% /media/robins/data_sdde
/dev/nvme0n1p1 34179072 30976360 1774344 95% /run/timeshift/backup
/dev/nvme0n1p2 73242624 28273672 44205288 40% /run/timeshift/backup-home

[Robbyx]

[tea for one;14013360]It seems that btrfs uses different commands to examine the file system.

I wonder if this link can provide any clues?


https://ohthehugemanatee.org/blog/20...ency-response/

I have run the script given by agvantibo. Thank you.

I have also followed by the guidance and link supplied by tea for one.

A.

sudo btrfs balance start -dusage=66 / &
[1] 23867
robins@robins-desktop:~$ Done, had to relocate 0 out of 44 chunks

[1]+  Done

B.

sudo btrfs fi usage /
Overall:
    Device size:		  32.60GiB
    Device allocated:		  32.56GiB
    Device unallocated:		  37.00MiB
    Device missing:		     0.00B
    Used:			  29.69GiB
    Free (estimated):		   1.40GiB	(min: 1.40GiB)
    Data ratio:			      1.00
    Metadata ratio:		      1.00
    Global reserve:		  74.88MiB	(used: 0.00B)

Data,single: Size:29.77GiB, Used:28.41GiB (95.43%)
   /dev/nvme0n1p1	  29.77GiB

Metadata,single: Size:2.76GiB, Used:1.28GiB (46.44%)
   /dev/nvme0n1p1	   2.76GiB

System,single: Size:32.00MiB, Used:16.00KiB (0.05%)
   /dev/nvme0n1p1	  32.00MiB

Unallocated:
   /dev/nvme0n1p1	  37.00MiB

Item B seems to be indicating that the free drive space has not changed much. It is still unclear what is taking up the extra space.

[Robbyx]

I noticed that the free diskspace dropped to 20mb after I restored a timeshift image of the root partition. My timeshift is set to use BTRFS.

I may have found what is happening to my disk space, but it is from reading other questions, so it might not be the actual cause. Please comment.

It seems that BTRFS creates snapshots that take up a lot of space. I do not know where to look for them in my system or what amount of free space in the root would prevent the error message of low free space appearing.

I do not know how to trim them without losing the benefits of BTRFS and timeshift. In the meantime, I have managed to add 20gb to the root from the home directory.

I could add more free space to the root if I knew how to move it there. I do not know how to move the unalocated area over the extended partition with gparted. How is it done?

nvme0n                                 size (gb)                          unused          Description    
p1                                          52                                      20                   root 
p2                                          50                                      24                   home
p3                                            1.8                                                          extended partition
                                              1.7                                                                   Unallocated space
p5                                                 100mb                                                            efi partition   
                                             165                                                             unallocated space
p4                                           643                                   135                     data storage

[Holger_Gehrke]

btrfs snapshots are sub-volumes. See https://btrfs.wiki.kernel.org/index....trfs-subvolume for sub-commands of the btrfs command for dealing with sub-volumes including listing them and deleting them. Also: sub-volumes reside on the same device(s) as the rest of the file system, they really shouldn't be used as backups because they won't protect you from failure of the device or of the file system. They only offer a quick way to recover from data loss due to user error or to roll back newly introduced misconfiguration(s).

You can't move unallocated space; you can move partitions. I usually use gparted from a live system on an USB-stick for that.

I don't understand why you have an extended partition; are you using the old mbr partitioning scheme on a system using UEFI which should be capable of using GPT ?

Holger

[Robbyx]

btrfs snapshots are sub-volumes. See https://btrfs.wiki.kernel.org/index....trfs-subvolume for sub-commands of the btrfs command for dealing with sub-volumes including listing them and deleting them. Also: sub-volumes reside on the same device(s) as the rest of the file system, they really shouldn't be used as backups because they won't protect you from failure of the device or of the file system. They only offer a quick way to recover from data loss due to user error or to roll back newly introduced misconfiguration(s).

You can't move unallocated space; you can move partitions. I usually use gparted from a live system on an USB-stick for that.

I don't understand why you have an extended partition; are you using the old mbr partitioning scheme on a system using UEFI which should be capable of using GPT ?

Holger

Thank you for your response

I have an EFI partition in the extended partition, but I do not remember why I made the EFI partition years ago, but I fear that if I deleted it, I might not be able to boot the system. My system is ASRock FM2a88X extreme6+, an sdde drive with the partitions shown in the comment, plus an ext HD. There is no bios, only Uefi. Only Ub 20.04 installed. Can I delete the EFI partiton safely?