Mysqldump failure during automatic backups (max_allowed_packet)

Bdzzld

• September 18, 2018 01:58

Hi, The last few weeks our automatic backups respond with a failure at database level for a specific database/user: [2018-09-18 02:44:43 +0200] username_master: mysqldump failed -- database may be corrupt
The logs show the following: username_master: mysqldump: Error 2020: Got packet bigger than 'max_allowed_packet' bytes when dumping table `TableName` at row: 12
As fas as I can tell, this can not be changed by the server administrator and is something set by cPanel. Please advise.

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  cPanelLauren

  • September 18, 2018 16:25

  Hi @Bdzzld This is set in mysql's configuration file. You can see it by running the following: grep packet /etc/my.cnf
  If you increase this value, restart mysql do you still encounter the same error? These are the MySQL defaults - not something set by cPanel necessarily. Thanks!

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  Bdzzld

  • September 18, 2018 18:01

  @cPanelLauren: All our cPanel servers have the following configured in /etc/my.cnf regarding mysqldump: [mysqldump] quick max_allowed_packet=16M
  The specific account is several years old and was back upped before without problems. The problem started to appear as of this month (the 4th to be exactly).

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  cPanelLauren

  • September 18, 2018 18:34

  hi @Bdzzld This is the setting for my server under [mysqld] and not specific to mysqldump running MariaDB 10.2: # grep max_allowed /etc/my.cnf max_allowed_packet=268435456
MariaDB [(none)]> show variables like '%max_all%'; +--------------------------+------------+ | Variable_name | Value | +--------------------------+------------+ | max_allowed_packet | 268435456 | | slave_max_allowed_packet | 1073741824 | +--------------------------+------------+ 2 rows in set (0.00 sec)
  I can confirm that these values have not been modified since I upgraded the server to MariaDB. It simply seems that the issue is the value is not high enough for your databases. The default for this limitation is 16MB per MySQL :: MySQL 5.7 Reference Manual :: B.5.2.9 Packet Too Large and Server System Variables

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