Help Center/ Cloud Container Engine/ User Guide/ Nodes/ Node O&M/ Optimizing Node System Parameters/ Changing the RuntimeMaxUse of the Memory Used by the Log Cache on a Node
Updated on 2024-08-16 GMT+08:00
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Changing the RuntimeMaxUse of the Memory Used by the Log Cache on a Node

Journald is a log system in Linux. It writes log information into binary files and uses /run/log/journal as the log cache directory by default. The Journald configuration file is stored in the /etc/systemd/journald.conf directory on the node. The RuntimeMaxUse parameter indicates the maximum memory usage of the log cache. If RuntimeMaxUse is not set, a large amount of memory will be occupied after the system runs for a long time.

The commands for modifying node system parameters are valid only when public images are used. The commands provided in this document are for reference only when private images are used.

Changing RuntimeMaxUse

  1. Log in to the node and view the /etc/systemd/journald.conf file. 

    cat /etc/systemd/journald.conf

  2. Modify RuntimeMaxUse. The recommended value is 100M.

    • If RuntimeMaxUse has been set in the journald.conf file, run the following command to change the value: 
      sed -i "s/RuntimeMaxUse=[0-9]*M/RuntimeMaxUse=100M/g" /etc/systemd/journald.conf && systemctl restart systemd-journald
    • If RuntimeMaxUse is not set in the journald.conf file, run the following command to add it: 
      echo RuntimeMaxUse=100M >> /etc/systemd/journald.conf && systemctl restart systemd-journald

  3. If the returned value is the same as the modified value, the modification is correct. 

    cat /etc/systemd/journald.conf | grep RuntimeMaxUse

Automatically Configuring RuntimeMaxUse When Creating a Node or Node Pool

You can set the script to be executed after a node or node pool is created. When creating a node or node pool, you can use the script to configure the RuntimeMaxUse size.

  1. Confirm the OS of the node or node pool to be created, for example, CentOS 7.6.
  2. Manually test the script commands on nodes in the same cluster and running the same OS. For details about how to manually run the script, see Changing RuntimeMaxUse.
  3. When creating a node or node pool, choose Advanced Settings > Post-installation Command to add commands. (The following commands must be configured after the verification is successful.)

    • Log in to the node and view the /etc/systemd/journald.conf file. If RuntimeMaxUse has been set, run the following command to change the value: 
      sed -i "s/RuntimeMaxUse=[0-9]*M/RuntimeMaxUse=100M/g" /etc/systemd/journald.conf && systemctl restart systemd-journald
    • Log in to the node and view the /etc/systemd/journald.conf file. If RuntimeMaxUse is not set, run the following command to add it: 
      echo RuntimeMaxUse=100M >> /etc/systemd/journald.conf && systemctl restart systemd-journald

    The command in the following figure is used only as an example. Change it as required.

  4. After the node is created, log in to the node to check whether the parameters are successfully modified. 

    cat /etc/systemd/journald.conf | grep RuntimeMaxUse

Parent Topic: Optimizing Node System Parameters