MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0
The innodb_directories variable,
which defines directories to scan at startup for tablespace files,
supports moving or restoring tablespace files to a new location
while the server is offline. During startup, discovered tablespace
files are used instead those referenced in the data dictionary,
and the data dictionary is updated to reference the relocated
files. If duplicate tablespace files are discovered by the scan,
startup fails with an error indicating that multiple files were
found for the same tablespace ID.
The directories defined by the
innodb_data_home_dir,
innodb_undo_directory, and
datadir variables are
automatically appended to the
innodb_directories argument
value. These directories are scanned at startup regardless of
whether an innodb_directories
setting is specified explicitly. The implicit addition of these
directories permits moving system tablespace files, the data
directory, or undo tablespace files without configuring the
innodb_directories setting.
However, settings must be updated when directories change. For
example, after relocating the data directory, you must update the
--datadir setting before
restarting the server.
The innodb_directories variable
can be specified in a startup command or MySQL option file. Quotes
are used around the argument value because a semicolon (;) is
interpreted as a special character by some command interpreters.
(Unix shells treat it as a command terminator, for example.)
Startup command:
mysqld --innodb-directories="directory_path_1;directory_path_2"
MySQL option file:
[mysqld] innodb_directories="directory_path_1;directory_path_2"
The following procedure is applicable to moving individual file-per-table and general tablespace files, system tablespace files, undo tablespace files, or the data directory. Before moving files or directories, review the usage notes that follow.
Stop the server.
Move the tablespace files or directories to the desired location.
Make the new directory known to InnoDB.
If moving individual
file-per-table
or general
tablespace files, add unknown directories to the
innodb_directories value.
The directories defined by the
innodb_data_home_dir,
innodb_undo_directory,
and datadir variables
are automatically appended to the
innodb_directories
argument value, so you need not specify these.
A file-per-table tablespace file can only be moved to
a directory with same name as the schema. For example,
if the actor table belongs to the
sakila schema, then the
actor.ibd data file can only be
moved to a directory named
sakila.
General tablespace files cannot be moved to the data directory or a subdirectory of the data directory.
If moving system tablespace files, undo tablespaces, or
the data directory, update the
innodb_data_home_dir,
innodb_undo_directory,
and datadir settings, as
necessary.
Restart the server.
Wildcard expressions cannot be used in the
innodb_directories argument
value.
The innodb_directories scan
also traverses subdirectories of specified directories.
Duplicate directories and subdirectories are discarded from
the list of directories to be scanned.
innodb_directories supports
moving InnoDB tablespace files. Moving
files that belong to a storage engine other than
InnoDB is not supported. This restriction
also applies when moving the entire data directory.
innodb_directories supports
renaming of tablespace files when moving files to a scanned
directory. It also supports moving tablespaces files to other
supported operating systems.
When moving tablespace files to a different operating system, ensure that tablespace file names do not include prohibited characters or characters with a special meaning on the destination system.
When moving a data directory from a Windows operating system
to a Linux operating system, modify the binary log file paths
in the binary log index file to use backward slashes instead
of forward slashes. By default, the binary log index file has
the same base name as the binary log file, with the extension
'.index'. The location of the binary log
index file is defined by
--log-bin. The default location
is the data directory.
If moving tablespace files to a different operating system
introduces cross-platform replication, it is the database
administrator's responsibility to ensure proper replication of
DDL statements that contain platform-specific directories.
Statements that permit specifying directories include
CREATE TABLE ...
DATA DIRECTORY and
CREATE
TABLESPACE ... ADD DATAFILE.
Add the directories of file-per-table and general tablespaces
created with an absolute path or in a location outside of the
data directory to the
innodb_directories setting.
Otherwise, InnoDB is not able to locate the
files during recovery. For related information, see
Tablespace Discovery During Crash Recovery.
To view tablespace file locations, query the Information
Schema FILES table:
mysql> SELECT TABLESPACE_NAME, FILE_NAME FROM INFORMATION_SCHEMA.FILES \G