Troubleshooting High Disk Space Utilisation – Linux
A full disk can affect your Linux server in many ways, services can stop working or working as intended or in extreme cases the server may become unresponsive. This article covers how to determine the status of your disk space and how to easily find any large folders and files on your system.
Commands in this article are to be run using an ssh or terminal connection to your server.
See the free space of your disks
Once you have ssh into your server, you can see the overall disk usage by running the following:
# df -h Filesystem Size Used Avail Use% Mounted on devtmpfs 3.9G 0 3.9G 0% /dev tmpfs 3.9G 4.0K 3.9G 1% /dev/shm tmpfs 3.9G 9.2M 3.9G 1% /run tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup /dev/sda3 92G 91G 1G 99% / /dev/sda1 950M 130M 820M 14% /boot /dev/loop0 3.9G 9.1M 3.7G 1% /tmp tmpfs 783M 0 783M 0% /run/user/0
This example shows amongst other filesystems that the root (/) filesystem is 99% used.
See directory size
Once you have determined that you are running out of space, you will want to find where the space is being used. Run the du command (as root) to check folder sizes:
du -hsx /*
# du -hsx /* 15G /backup 0 /bin 98M /boot 0 /dev 69M /etc 14G /home 0 /lib 0 /lib64 0 /media 0 /mnt 602M /opt 0 /proc 33M /root 9.2M /run 0 /sbin 0 /srv 0 /sys 1000K /tmp 80G /usr 3.9G /var
As you can see, /usr is 80GB in size.
Using the example, you can then go further into /usr to see which subdirectory is using the most space
# du -hsx /usr/* 403M /usr/bin 0 /usr/etc 0 /usr/games 33M /usr/include 890M /usr/lib 586M /usr/lib64 86M /usr/libexec 2.8G /usr/local 595M /usr/sbin 499M /usr/share 0 /usr/src 75G /usr/tmp 195M /usr/tmpDSK
This shows /usr/tmp as 75G. You would then run du on /usr/tmp and so on until you pinpoint the directory or files that are using up the disk space.
The find command is useful when you want to search through directory trees on a hard drive.
You can locate files and / or directories based on some user-specified criteria and you can even run a specific action on these files / directories using a program such as xargs.
Use find followed by the path to show everything (files, folders and more) under that path.
Find something by type
By using the -type option you can specify files (-type f), directories (-type d), or even symbolic links (-type l)
find /home/ -type d
This would find all directories under home.
Find a file by size
You can search for a file by a specific size but in most situations you won’t know the exact size, so by adding a + means this size or larger, and a – means this size or smaller.
Find a file greater than 1 Gigabyte
find /home/ -type f -size +1G
You can specify sizes in Kilobytes (k) and Megabyte (M)
find /home/ -type f -size +200M
To find files less than a specific size, use – instead
find /home/ -type f -size -50M
You can also combine the two to find files in between a size range
find /home/ -type f -size +700M -size -900M