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Knowledge Base

MySQL/MariaDB crashes periodically on Plesk: Out of memory

 
databasedatabase serverdatabaseskernellinux

Applicable to:

  • Plesk for Linux

Symptoms

  • Plesk and websites are down from time to time:

    503 Service Unavailable


    Server Error
    500
    Zend_Db_Adapter_Exception
    SQLSTATE[HY000] [2002] Connection refused


    ERROR: PleskDBException: Unable to connect to database: mysql_connect(): Connection refused /var/lib/mysql/mysql.sock (Error code: 2002). Please check that database server is started and accessible. (Abstract.php:69)

Cause

Insufficient amount of free RAM on the server.

  • In the log file /var/log/mariadb/mariadb.log or /var/log/mysql/mysql.log, the following error messages are found:

    InnoDB: Fatal error: cannot allocate memory for the buffer pool
    [ERROR] Plugin 'InnoDB' init function returned error.
    [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
    [ERROR] mysqld: Out of memory (Needed 128917504 bytes)
    [ERROR] mysqld: Out of memory (Needed 96681984 bytes)

  • The following error messages can be found in the log file /var/log/messages:

    kernel: Free swap = 0kB kernel: Total swap = 2097148kB ...
    kernel: Out of memory: Kill process 21770 (mysqld) score 17 or sacrifice child
    kernel: Killed process 21770 (mysqld) total-vm:2698392kB, anon-rss:24616kB, file-rss:0kB, shmem-rss:0kB

Resolution

Contact the server administrator or provider to increase the amount of the server's RAM and add swap if it is not enabled.

Read the full article
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