I will try to describe the issue with as many details as possible.
I have a Digital Ocean server 1GB RAM, 25GB SSD with Ubuntu 16.04. I have a docker container (docker version is: Docker version 18.03.0-ce, build 0520e24).
The docker container contains postfix, dovecot, mysql, roundcube and a few other services.
Everything works fine but when start to receive or send emails the free space diminishes and I end up with no free space.
Before that happens if I run “df -h” I get:
root@mail:~# df -h Filesystem Size Used Avail Use% Mounted on udev 488M 0 488M 0% /dev tmpfs 100M 9.3M 90M 10% /run /dev/vda1 25G 11G 14G 46% / tmpfs 497M 0 497M 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs 497M 0 497M 0% /sys/fs/cgroup /dev/vda15 105M 3.4M 102M 4% /boot/efi overlay 25G 11G 14G 46% /var/lib/docker/overlay2/17795ba052726099d7ca962eb9756c8e5354483e388c3e326781249954172746/merged shm 64M 0 64M 0% /var/lib/docker/containers/559088336f8c6948d6940714b7e97aea765bc98ee6f237afe39406b2f3638e67/mounts/shm
When I run out of space “/dev/vda1” says “Used space 25GB” and also “overlay” says “Used 25GB”.
When I access the docker container:
docker attach SOME_ID
and I try to find directories and files of significant size or directories and files generated recently…supposing that in this way I will find the source of the issue…I can’t find anything.
This is quite confusing because according to “df -h” there is no free space and the issue is in the docker container but when I try to find suspicious files I can’t find any.
And also, if I reboot the whole machine (Turn off -> Turn on) the used space is emptied and the mail server gets back to normal. In a few days the issue happens again. The server runs out of space and I have to reboot it again.
May I please ask you for advice how to trace the source of the issue?
This textbox defaults to using Markdown to format your answer.
You can type !ref in this text area to quickly search our full set of tutorials, documentation & marketplace offerings and insert the link!
These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.
Join our DigitalOcean community of over a million developers for free! Get help and share knowledge in Q&A, subscribe to topics of interest, and get courses and tools that will help you grow as a developer and scale your project or business.
Click below to sign up and get $200 of credit to try our products over 60 days!