Because the InnoDB storage engine introduces a new file format, with new on-disk data structures within both the database and log files, there are important restrictions on the use of the plugin in typical user environments. Specifically, you should pay special attention to the information presented here about file format compatibility with respect to the following scenarios:

WARNING: Once you use the InnoDB storage engine on a set of database files, care must be taken to avoid crashes and corruptions when using those files with an earlier version of InnoDB, as might happen by opening the database with MySQL when the plugin is not installed. It is strongly recommended that you use a “slow shutdown” (SET GLOBAL innodb_fast_shutdown=0) when stopping the MySQL server when the InnoDB storage engine is enabled. This ensures log files and other system information written by the plugin does not cause problems when using a prior version of InnoDB. See Section 11.3, “How to Downgrade”.

WARNING: If you dump a database containing compressed tables with mysqldump, the dump file may contain CREATE TABLE commands that attempt to create compressed tables, or those using ROW_FORMAT=DYNAMIC in the new database. Therefore, be sure the new database is running the InnoDB storage engine, with the proper settings for innodb_file_format and innodb_file_per_table, if you want to have the tables re-created as they exist in the original database. Typically, however, when the mysqldump file is loaded, MySQL and InnoDB ignore CREATE TABLE options they do not recognize, and the table(s) are created in a format used by the running server.

WARNING: If you use MySQL replication, you should be careful to ensure all slaves are configured with the InnoDB storage engine, with the same settings for innodb_file_format and innodb_file_per_table. If you do not do so, and you create tables that require the new “Barracuda” file format, replication errors may occur. If a slave MySQL server is running the built-in InnoDB, it ignores the CREATE TABLE options to create a compressed table or one with ROW_FORMAT=DYNAMIC, and create the table uncompressed, with ROW_FORMAT=COMPACT.

WARNING: Version 3.0 of InnoDB Hot Backup does not support the new “Barracuda” file format. Using InnoDB Hot Backup Version 3 to backup databases in this format causes unpredictable behavior. A future version of InnoDB Hot Backup is expected to support databases used with the InnoDB storage engine. As an alternative, you can back up such databases with mysqldump.