system tablespace
By default, this single data file stores all the table data for a database, as well as all the metadata for InnoDB-related objects (the data dictionary).
Turning on the innodb-file-per-table option causes each newly created table to be stored in its own tablespace, reducing the size of, and dependencies on, the system tablespace.
In MariaDB 5.6 and higher, setting a value for the innodb-undo_tablespaces option splits the undo log into one or more separate tablespace files. These files are still considered part of the system tablespace.
Keeping all table data in the system tablespace has implications for the MySQL Enterprise Backup product (backing up one large file rather than several smaller files), and prevents you from using certain InnoDB features that require the newer file format known as Barracuda.
See also Barracuda.
See also data dictionary.
See also file format.
See also file-per-table.
See also ibdata file.
See also innodb-file-per-table.
See also MySQL Enterprise Backup.
See also tablespace.
See also undo log.