Too many files in directories like /tmp/systemd-private- cause server crash due to lack of disk space

• Plesk Obsidian running on a Linux-based operating system
• The server crashes due to lack of disk space

• In the
/tmp directory of the Linux server operating system, there are many subdirectories with names that are similar to the following:

  /tmp/systemd-private-9301532e5ff749e388f365a25f51e9ea-mariadb.service-zvKlrX/tmp/
  /tmp/systemd-private-9301532e5ff749e388f365a25f51e9ea-httpd.service-HRR15v/

• Many system services have
PrivateTmp set to
true:

  # grep -R PrivateTmp /etc/systemd/
  /etc/systemd/system/multi-user.target.wants/named-chroot.service:PrivateTmp=false
  /etc/systemd/system/multi-user.target.wants/php-fpm.service:PrivateTmp=true
  /etc/systemd/system/multi-user.target.wants/httpd.service:PrivateTmp=true
  /etc/systemd/system/multi-user.target.wants/mariadb.service:PrivateTmp=true

• The temporary subdirectories created in /tmp are using up all of the disk space and cause the server crash

Cause

The PrivateTmp systemd feature is enabled for the services mentioned in the subdirectory names of /tmp. Configuring a systemd service with PrivateTmp=true leads to the fact that the service starts using a private tmp directory and creates subdirectories within the /tmp server directory that store its temporary files. There are a lot of files in the created subdirectories and this causes lack of disk space.

Resolution

Solution 1

1. Log into your server via SSH

2. Configure the temporary file rotation to happen as often as you need it to by opening the file
/usr/lib/tmpfiles.d/tmp.conf with your favorite command-line text editor.

3. When you open the file, you will see lines that are similar ot the following:

#Clear tmp directories separately, to make them easier to override
#Type Path Mode User Group Age Argument
v /tmp 1777 root root 10d
v /var/tmp 1777 root root 30d
3. Save the changes

Note: The configuration file has a special syntax. Every line is a rule. Each line in the tmpfiles.d configuration file is separated by tabs or spaces into seven columns that define a rule. More information related to the possible configurations is available here.

Solution 2

Disable the PrivateTmp systemd feature for the service (example, for MariaDB):

1. Check which services have
PrivateTmp set to
true:

   # grep -R PrivateTmp /etc/systemd/
   /etc/systemd/system/multi-user.target.wants/named-chroot.service:PrivateTmp=false
   /etc/systemd/system/multi-user.target.wants/php-fpm.service:PrivateTmp=true
   /etc/systemd/system/multi-user.target.wants/httpd.service:PrivateTmp=true
   /etc/systemd/system/multi-user.target.wants/mariadb.service:PrivateTmp=true

2. Stop the service:

   # systemctl stop mariadb

3. Change
PrivateTmp value to
false
in the file
/etc/systemd/system/multi-user.target.wants/mariadb.service

4. Reload
systemd:

   # systemctl daemon-reload

5. Start
mariadb:

   # systemctl start mariadb