InnoDB Table and Page Compression Table 15.11 Automatically Configured Number of Log Files Buffer Pool Size Number of Log Files Less than 8GB ROUND( buffer pool size ) 8GB to 128GB ROUND( buffer pool size  * 0.75) Greater than 128GB 64 The flush method is set to  O_DIRECT_NO_FSYNC  when  innodb_dedicated_server  is enabled. If the O_DIRECT_NO_FSYNC  setting is not available, the default  innodb_flush_method  setting is used. • innodb_flush_method Note The minimum  innodb_log_files_in_group  value of 2 is enforced if the rounded buffer pool size value is less than 2GB. InnoDB  uses  O_DIRECT  during flushing I/O, but skips the  fsync()  system call after each write operation. Warning Prior to MySQL 8.0.14, this setting is not suitable for file systems such as XFS and EXT4, which require an  fsync()  system call to synchronize file system metadata changes. As of MySQL 8.0.14,  fsync()  is called after creating a new file, after increasing file size, and after closing a file, to ensure that file system metadata changes are synchronized. The  fsync()  system call is still skipped after each write operation. Data loss is possible if redo log files and data files reside on different storage devices, and an unexpected exit occurs before data file writes are flushed from a device cache that is not battery-backed. If you use or intend to use different storage devices for redo log files and data files, and your data files reside on a device with a cache that is not battery-backed, use  O_DIRECT  instead. If an automatically configured option is configured explicitly in an option file or elsewhere, the explicitly specified setting is used, and a startup warning similar to this is printed to  stderr : [Warning] [000000] InnoDB: Option innodb_dedicated_server is ignored for innodb_buffer_pool_size because innodb_buffer_pool_size=134217728 is specified explicitly. Explicit configuration of one option does not prevent the automatic configuration of other options. If  innodb_dedicated_server  is enabled and  innodb_buffer_pool_size  is configured explicitly in an option file,  innodb_log_file_size  and  innodb_log_files_in_group  are still automatically configured based on a buffer pool size value calculated according to the amount of memory detected on the server, even though that value is not used to configure the size of the buffer pool. Automatically configured settings are evaluated and reconfigured if necessary each time the MySQL server is started. 15.9 InnoDB Table and Page Compression 3146