Good day @ibrahimemrekaya,

MySQL backups with xtrabackup (Percona) are failing due to following error -

MySQLBackupChild.log

198650 307fa 02/18 17:08:32 33  MySqlChildProcess::Wait() - Child died after receiving signal 2
198650 307fa 02/18 17:08:32 33  MySqlBackupDb::writeDataToPipe() - Wait returned failure
198650 307fa 02/18 17:08:32 33  MySqlBackupDb::writeDataToPipe() - last buffer=u]
198650 307fa 02/18 17:08:32 33  MySqlBackupDb::writeDataToPipe() - STDERR: smysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) when trying to connect
]
198650 307fa 02/18 17:08:32 33  MySqlBackupDb::DoBackupDbUsingPipe() - writeDataToPipe failed
198650 307fa 02/18 17:08:32 33  ::MySqlClBackupBase::DoBackupMySql() - MySqlClBackupBase::DoBackupDb returned error
198650 307fa 02/18 17:08:32 33  ::MySqlClBackupBase::DoBackupMySql() - Performance counter enabled from Registry
198650 307fa 02/18 17:08:32 33  ::MySqlClBackupBase::DoBackupMySql() - Analysing Database = Dmysql]
198650 307fa 02/18 17:08:32 33  GetMySqlInfoExt::CheckDBPresence() - Checking DB Presence Failed...Probably connection to Server not present or Querying Server failed
198650 307fa 02/18 17:08:32 33  ::CheckDbExistence() - database found in server... will continue to dump...
198650 307fa 02/18 17:08:32 33  MySqlBackupDb::DoBackupDbUsingPipe() -  reg key bUseSingleTransaction is either not set or fetch not succeeded.
198650 307fa 02/18 17:08:32 33  GetMySqlInfoExt::QueryVariable() - cannot query variable 2002:Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)]
198650 307fa 02/18 17:08:32 33  GetMySqlInfoExt::GetVersionFromServer() - Server version : 8.0.25-15
198650 307fa 02/18 17:08:32 33  GetMySqlInfoExt::QueryVariable() - cannot query variable o2002:Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)]
198650 307fa 02/18 17:08:32 33  GetMySqlInfo::isMariaDb() - cannot get 'version_comment' value from server.
198650 307fa 02/18 17:08:32 33  GetMySqlInfoExt::isMySQL8orMore() - MariaDB check failed.

Could you try the following 

1#

Set the value for the max_allowed_packet variable as 1GB in the MySQL server.

However, you can set a different value for the client by configuring the value for sAdvancedBackupOptions.

The value set on the client is given priority over the one set on MySQL server.

 2#

Increase the value for the connect_timeout variable on the MySQL server to 100.

3#

For more information check the troubleshooting section https://documentation.commvault.com/11.24/expert/19483_backup_troubleshooting_mysql_agent.html

Hi @Gowri Shankar,

Thank you for the information. I sent this to our customer. I’ll get back to you.

Regards,

İbrahim

Hi,

We opened a case. Case number is: 220225-223.

Sharing case solution (removed anything identifiable):

Finding Details:

MYSQL backup failed with error, message is: STDERR: [mysqldump: Got error: 2002: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) when trying to connect ]

Solution:

We reviewed the Mysql system logs -


2022-03-19T14:21:01.309942Z 355128 [Warning]  Open files 3006 exceeds the limit 3000
2022-03-19T14:22:48.124888Z 0 Warning] MY-012152] InnoDB] Open files 3007 exceeds the limit 3000


2022-03-21T12:19:24.056857Z 0 Warning] MY-012152] ] Open files 3006 exceeds the limit 3000
2022-03-21T12:20:52.935081Z 0 System] MY-013172] Server] Received SHUTDOWN from user . Shutting down mysqld (Version: 8.0.25-15).
2022-03-21T12:20:58.300995Z 0 0Warning] ]MY-012152] ]] Open files 3006 exceeds the limit 3000
2022-03-21T12:21:07.196052Z 0 0System] ]MY-010910] ]Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.25-15) Percona Server (GPL), Release '15', Revision 'a558ec2'.
""""2022-03-21T12:21:20.435843Z 0 0Warning] ]MY-010140] ]Server] Could not increase number of max_open_files to more than 10000 (request: 100000)
2022-03-21T12:21:20.435855Z 0 0Warning] ]MY-010141] ]Server] Changed limits: max_connections: 9190 (requested 20000)
2022-03-21T12:21:20.435862Z 0 0Warning] ]MY-010142] ]Server] Changed limits: table_open_cache: 400 (requested 4096)
2022-03-21T12:21:20.735640Z 0 0Warning] ]MY-010915] ]Server] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release.
2022-03-21T12:21:20.738821Z 0 0System] ]MY-010116] ]Server] /usr/sbin/mysqld (mysqld 8.0.25-15) starting as process 899
2022-03-21T12:21:20.803633Z 1 1System] ]MY-013576] ]] initialization has started.
2022-03-21T12:21:29.656096Z 1 1System] ]MY-013577] ]] initialization has ended.
2022-03-21T12:21:33.311401Z 0 0System] ]MY-011323] ]Server] X Plugin ready for connections. Bind-address: '0.0.0.0' port: 33060, socket: /var/run/mysqld/mysqlx.sock
mysqld: File '/var/log/mysql/TCMX-SQL-TEMPLA-slow.log' not found (OS errno 13 - Permission denied)
2022-03-21T12:21:33.370809Z 0 0ERROR] ]MY-011263] ]Server] Could not use /var/log/mysql/TCMX-SQL-TEMPLA-slow.log for logging (error 13 - Permission denied). Turning logging off for the server process. To turn it on again: fix the cause, then either restart the query logging by using "SET GLOBAL SLOW_QUERY_LOG=ON" or restart the MySQL server.
2022-03-21T12:21:36.924943Z 0 0Warning] ]MY-010068] ]Server] CA certificate ca.pem is self signed.
2022-03-21T12:21:36.925652Z 0 0System] ]MY-013602] ]Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
2022-03-21T12:21:37.199949Z 0 0System] ]MY-010931] ]Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.25-15' socket: '/var/run/mysqld/mysqld.sock' port: 3306 Percona Server (GPL), Release '15', Revision 'a558ec2'.
2022-03-21T12:25:44.409491Z 300 0Warning] ]MY-012152] ]] Open files 3006 exceeds the limit 3000
2022-03-21T12:28:23.553040Z 0 0Warning] ]MY-012152] ]] Open files 3006 exceeds the limit 3000


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Please review this internally regarding the same as why the backups causes DB connectivity issues.