content_image/795422.jpg content_image/795423.jpg content_image/795424.jpg
<img src='content_image/795422.jpg'>

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” . 

• innodb_doublewrite_pages 

<img src='content_image/795423.jpg'>

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” . 

• innodb_extend_and_initialize 

<img src='content_image/795424.jpg'>

Controls how space is allocated to file-per-table and general tablespaces on Linux systems. 

