How can a partition be full if du does not show it is? (via: linux – Super User) #OpenSuSE #btrfs #snapshots

A long time ago I asked this OpenSuSE/Linux question: How can a partition be full if du does not show it is? – Linux on Super User.

With help of the OpenSuSE forums, I did figure out the source of the problem and solution, but I totally forgot to blog about it.

So below it is, just in case SuperUser ever shuts down, or the StackOverflow moderators are taking over SuperUser as well.

But first the comments in the questions about where I found the source and solution:

I found it through the openSUSE forums: it uses btrfs and snapshots. So the snapshots take up a lot of space. And I need to find out a way to delete old snapshots. forums.opensuse.org/english/get-technical-help-here/…

and

I think I found it: nrtm.org/index.php/2012/03/13/…

I wasn’t alone, so here are some more useful links and links from people asking for help:

• NerdyRoom™ » The joys of btrfs and OpenSuSE – or “no space left on device”.
• 13.1 : dual boot, btrfs and root partition.
• Chapter 4. Snapshots/Rollback with Snapper | ActiveDoc.
• Chapter 3. Advanced Disk Setup | ActiveDoc.
• Suse Doc: Storage Administration Guide – Btrfs Error: No space is left on device – December 16 2013.
• Ubuntu thinks btrfs disk is full but its not – Ask Ubuntu.
• An introduction to system snapshot and rollback with Snapper and BtrFS on SLES 11 SP2 – Conversations | SUSE.
• No space left on device! SSD, snapper, btrfs, making it all work in openSUSE 13.2 | silviumc.
• OS 13.2 doesnt boot: – no space left on device.
• Think my openSUSE install has died! – Linux – PC Pitstop Forums.
• filesystems – btrfs on openSUSE not releasing disk space – Unix & Linux Stack Exchange.

–jeroen

PS: here is my SE question on it: linux – How can a partition be full if du does not show it is? – Super User.

Question: How can a partition be full if du does not show it is?

On one of my systems, the root partition is full:

snip:˜ # df -h
Filesystem      Size  Used Avail Use% Mounted on
rootfs           11G  9.3G     0 100% /
devtmpfs        744M   36K  744M   1% /dev
tmpfs           751M     0  751M   0% /dev/shm
tmpfs           751M  296K  751M   1% /run
/dev/sda7        11G  9.3G     0 100% /
tmpfs           751M     0  751M   0% /sys/fs/cgroup
tmpfs           751M  296K  751M   1% /var/lock
tmpfs           751M  296K  751M   1% /var/run
tmpfs           751M     0  751M   0% /media
/dev/sda5       151M   39M  104M  28% /boot
/dev/sda8       4.4G  207M  3.3G   6% /home

But du does not show near 9.3 gigabyte of usage:

snip:~ # du /* -s -h
5.2M    /bin
34M     /boot
36K     /dev
22M     /etc
199M    /home
154M    /lib
20M     /lib64
0       /media
0       /mnt
0       /opt
0       /proc
7.9M    /root
288K    /run
7.1M    /sbin
0       /selinux
756K    /srv
0       /sys
0       /tmp
1.6G    /usr
1.1G    /var

It only accounts for about 3 gigabytes.

• How can that be?
• Where should I look for the remaining 6+ gigabytes of used gigabytes?

I’m using openSUSE 12.2:

snip:~ # cat /etc/SuSE-release
openSUSE 12.2 (x86_64)
VERSION = 12.2
CODENAME = Mantis

Answer:

First some background information

btrfs filesystem df /

for i in `seq 1 3656`; do snapper delete $i; done