“unknown variable 'key_buffer_size=256M'” when trying to mysqldump

Question

I have a dedicated 32 GB RAM Centos 7 server. I have very limited knowledge about setting of /etc/my.cnf . I encounter “unknown variable 'key_buffer_size=256M'” during backup and as a result, system create zero size files.

mysqldump: unknown variable 'key_buffer_size=256M' Database Backup: bor --> bor.sql building file list ... done bor.sql

sent 105 bytes received 46 bytes 302.00 bytes/sec total size is 0 speedup is 0.00

I couldn't understand what is the problem with key_buffer_size !

Here is the content of my "my.cnf":

!includedir /etc/my.cnf.d

key_buffer_size = 256M
query_cache_size = 128M
tmp_table_size = 128M
innodb_buffer_pool_size = 6500M
innodb_additional_mem_pool_size = 32M
innodb_log_buffer_size = 8M
max_connections = 250
sort_buffer_size = 8M
read_buffer_size = 2M
read_rnd_buffer_size = 16M
join_buffer_size = 8M
binlog_cache_size = 1M

Answer 1

look at your MySQL my.cnf [mysqldump] Here you do not add your own key_buffer_size=256M You can cancel this parameter

Answer 2

Just before key_buffer_size = 256M, add a line:

[mysqld]