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When the autoextend  attribute is specified, the data file automatically increases in size by 64MB increments as space is required. The innodb_autoextend_increment  variable controls the increment size. 

To specify a maximum size for an auto-extending data file, use the max  attribute following the autoextend  attribute. Use the max  attribute only in cases where constraining disk usage is of critical importance. The following configuration permits ibdata1  to grow to a limit of 500MB: 

[mysqld] innodb_data_file_path=ibdata1:12M:autoextend:max:500M 

A minimum file size is enforced for the first  system tablespace data file to ensure that there is enough space for doublewrite buffer pages. The following table shows minimum file sizes for each InnoDB  page size. The default InnoDB  page size is 16384 (16KB). 

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If your disk becomes full, you can add a data file on another disk. For instructions, see Resizing the System Tablespace. 

The size limit for individual files is determined by your operating system. You can set the file size to more than 4GB on operating systems that support large files. You can also use raw disk partitions as data files. See Using Raw Disk Partitions for the System Tablespace. 

InnoDB  is not aware of the file system maximum file size, so be cautious on file systems where the maximum file size is a small value such as 2GB. 

System tablespace files are created in the data directory by default ( datadir ). To specify an alternate location, use the innodb_data_home_dir  option. For example, to create a system tablespace data file in a directory named myibdata , use this configuration: 

[mysqld] innodb_data_home_dir = /myibdata/ innodb_data_file_path=ibdata1:50M:autoextend 

A trailing slash is required when specifying a value for innodb_data_home_dir . InnoDB  does not create directories, so ensure that the specified directory exists before you start the server. Also, ensure sure that the MySQL server has the proper access rights to create files in the directory. 

InnoDB  forms the directory path for each data file by textually concatenating the value of innodb_data_home_dir  to the data file name. If innodb_data_home_dir  is not defined, the default value is “./” , which is the data directory. (The MySQL server changes its current working directory to the data directory when it begins executing.) 

Alternatively, you can specify an absolute path for system tablespace data files. The following configuration is equivalent to the preceding one: 

[mysqld] innodb_data_file_path=/myibdata/ibdata1:50M:autoextend 

When you specify an absolute path for innodb_data_file_path , the setting is not concatenated with the innodb_data_home_dir  setting. System tablespace files are created in the specified absolute path. The specified directory must exist before you start the server. 

