server with  --skip-innodb-doublewrite . Consider disabling the doublewrite buffer if you are more concerned with performance than data integrity, as may be the case when performing benchmarks, for example. Doublewrite Buffer If the doublewrite buffer is located on a Fusion-io device that supports atomic writes, the doublewrite buffer is automatically disabled and data file writes are performed using Fusion-io atomic writes instead. However, be aware that the  innodb_doublewrite  setting is global. When the doublewrite buffer is disabled, it is disabled for all data files including those that do not reside on Fusion-io hardware. This feature is only supported on Fusion-io hardware and is only enabled for Fusion-io NVMFS on Linux. To take full advantage of this feature, an  innodb_flush_method  setting of  O_DIRECT  is recommended. The  innodb_doublewrite_dir  variable (introduced in MySQL 8.0.20) defines the directory where InnoDB  creates doublewrite files. If no directory is specified, doublewrite files are created in the innodb_data_home_dir  directory, which defaults to the data directory if unspecified. A hash symbol ’#’ is automatically prefixed to the specified directory name to avoid conflicts with schema names. However, if a ’.’, ’#’. or ’/’ prefix is specified explicitly in the directory name, the hash symbol ’#’ is not prefixed to the directory name. Ideally, the doublewrite directory should be placed on the fastest storage media available. The  innodb_doublewrite_files  variable defines the number of doublewrite files. By default, two doublewrite files are created for each buffer pool instance: A flush list doublewrite file and an LRU list doublewrite file. The flush list doublewrite file is for pages flushed from the buffer pool flush list. The default size of a flush list doublewrite file is the  InnoDB  page size * doublewrite page bytes. The LRU list doublewrite file is for pages flushed from the buffer pool LRU list. It also contains slots for single page flushes. The default size of an LRU list doublewrite file is the  InnoDB  page size * (doublewrite pages + (512 / the number of buffer pool instances)) where 512 is the total number of slots reserved for single page flushes. 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.) Doublewrite file names have the following format:  #ib_ page_size _ file_number .dblwr . For example, the following doublewrite files are created for a MySQL instance with an  InnoDB  pages size of 16KB and a single buffer pool: #ib_16384_0.dblwr #ib_16384_1.dblwr The  innodb_doublewrite_files  variable is intended for advanced performance tuning. The default setting should be suitable for most users. The  innodb_doublewrite_pages  variable (introduced in MySQL 8.0.20) controls the maximum number of doublewrite pages per thread. If no value is specified,  innodb_doublewrite_pages  is set to the  innodb_write_io_threads  value. This variable is intended for advanced performance tuning. The default value should be suitable for most users. • innodb_doublewrite_pages 3073 • innodb_doublewrite_dir • innodb_doublewrite_files