InnoDB System Variables Defines the number of doublewrite files. By default, two doublewrite files are created for each buffer pool instance. At a minimum, there are two doublewrite files. The maximum number of doublewrite files is two times the number of buffer pool instances. (The number of buffer pool instances is controlled by the innodb_buffer_pool_instances  variable.) For more information, see Section 15.6.4, “Doublewrite Buffer” . Defines the maximum number of doublewrite pages per thread for a batch write. If no value is specified, innodb_doublewrite_pages  is set to the  innodb_write_io_threads  value. For more information, see Section 15.6.4, “Doublewrite Buffer” . Controls how space is allocated to file-per-table and general tablespaces on Linux systems. • innodb_extend_and_initialize • innodb_doublewrite_pages Dynamic No SET_VAR  Hint Applies No Type Integer Default Value innodb_buffer_pool_instances * 2 Minimum Value 2 Maximum Value 256 Command-Line Format --innodb-doublewrite-pages=# Introduced 8.0.20 System Variable innodb_doublewrite_pages Scope Global Dynamic No SET_VAR  Hint Applies No Type Integer Default Value innodb_write_io_threads value Minimum Value innodb_write_io_threads value Maximum Value 512 Command-Line Format --innodb=extend-and-initialize[={OFF| ON}] Introduced 8.0.22 System Variable innodb_extend_and_initialize Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Boolean Default Value ON 3240