After restarting the server on Linux, the problem with the database, how to solve?

Question

1C-Bitrix

Hello!
After turning off and on the server (Linux) where the site is located on Bitrix, there is a problem with the database, it gives the following error:

[Bitrix\Main\DB\ConnectionException] 
Mysql connect error [localhost]: (2002) No such file or directory (400)
/var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/db/mysqliconnection.php:65
#0: Bitrix\Main\DB\MysqliConnection->connectInternal()
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/db/mysqliconnection.php:122
#1: Bitrix\Main\DB\MysqliConnection->queryInternal(string, array, NULL)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/db/connection.php:329
#2: Bitrix\Main\DB\Connection->query(string)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/config/option.php:182
#3: Bitrix\Main\Config\Option::load(string, NULL)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/config/option.php:53
#4: Bitrix\Main\Config\Option::get(string, string, string)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/httprequest.php:337
#5: Bitrix\Main\HttpRequest->prepareCookie(array)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/httprequest.php:63
#6: Bitrix\Main\HttpRequest->__construct(object, array, array, array, array)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/httpapplication.php:42
#7: Bitrix\Main\HttpApplication->initializeContext(array)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/lib/application.php:122
#8: Bitrix\Main\Application->initializeExtendedKernel(array)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/include.php:23
#9: require_once(string)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/include/prolog_before.php:14
#10: require_once(string)
  /var/www/univerokrug.hse.perm.ru/bitrix/modules/main/include/prolog.php:10
#11: require_once(string)
  /var/www/univerokrug.hse.perm.ru/bitrix/header.php:1
#12: require(string)
  /var/www/univerokrug.hse.perm.ru/index.php:2

What could be the problem?

Answer 1

show output

1. journalctl -xe
   
2. df-h
   
3. ls -Al /var/lib/mysql
   

Answer 2

A similar problem - the place on the server ran out and the database could not start.