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MySQL 5.0 Reference Manual :: 18 MySQL Cluster :: 18.9 On-line Backup of MySQL Cluster :: 18.9.3 ndb_restore — Restore a Cluster Backup
18.9.4 Configuration for Cluster Backup »
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18.9.3. ndb_restore — Restore a Cluster Backup

The cluster restoration program is implemented as a separate command-line utility ndb_restore, which can normally be found in the MySQL bin directory. This program reads the files created as a result of the backup and inserts the stored information into the database.

ndb_restore must be executed once for each of the backup files that were created by the START BACKUP command used to create the backup (see Section 18.9.2, “Using The Management Client to Create a Backup”). This is equal to the number of data nodes in the cluster at the time that the backup was created.

Note

Before using ndb_restore, it is recommended that the cluster be running in single user mode, unless you are restoring multiple data nodes in parallel. See Section 18.7.4, “Single User Mode”, for more information about single user mode.

Typical options for this utility are shown here: 

ndb_restore [-c connectstring] -n node_id [-m] -b backup_id -r [backup_path=]/path/to/backup/files

The -c option is used to specify a connectstring which tells ndb_restore where to locate the cluster management server. (See Section 18.3.4.2, “The Cluster Connectstring”, for information on connectstrings.) If this option is not used, then ndb_restore attempts to connect to a management server on localhost:1186. This utility acts as a cluster API node, and so requires a free connection “slot” to connect to the cluster management server. This means that there must be at least one [api] or [mysqld] section that can be used by it in the cluster config.ini file. It is a good idea to keep at least one empty [api] or [mysqld] section in config.ini that is not being used for a MySQL server or other application for this reason (see Section 18.3.4.6, “Defining SQL and Other API Nodes”).

You can verify that ndb_restore is connected to the cluster by using the SHOW command in the ndb_mgm management client. You can also accomplish this from a system shell, as shown here: 

shell> ndb_mgm -e "SHOW"

-n is used to specify the node ID of the data node on which the backups were taken.

The first time you run the ndb_restore restoration program, you also need to restore the metadata. In other words, you must re-create the database tables — this can be done by running it with the -m option. Note that the cluster should have an empty database when starting to restore a backup. (In other words, you should start ndbd with --initial prior to performing the restore.)

The -b option is used to specify the ID or sequence number of the backup, and is the same number shown by the management client in the Backup backup_id completed message displayed upon completion of a backup. (See Section 18.9.2, “Using The Management Client to Create a Backup”.)

The path to the backup directory is required, and must include the subdirectory corresponding to the ID backup of the backup to be restored. For example, if the data node's DataDir is /var/lib/mysql-cluster, then the backup directory is /var/lib/mysql-cluster/BACKUP, and the backup files for the backup with the ID 3 can be found in /var/lib/mysql-cluster/BACKUP/BACKUP-3. The path may be absolute or relative to the directory in which the ndb_restore executable is located, and may be optionally prefixed with backup_path=.

Important

When restoring cluster backups, you must be sure to restore all data nodes from backups having the same backup ID. Using files from different backups will at best result in restoring the cluster to an inconsistent state, and may fail altogether.

Important

It is not possible to restore a backup made from a newer version of MySQL Cluster using an older version of ndb_restore. You can restore a backup made from a newer version of MySQL to an older cluster, but you must use a copy of ndb_restore from the newer MySQL Cluster version to do so.

For example, to restore a cluster backup taken from a cluster running MySQL 5.0.45 to a cluster running MySQL Cluster 5.0.41, you must use a copy of ndb_restore from the 5.0.45 distribution.

It is possible to restore a backup to a database with a different configuration than it was created from. For example, suppose that a backup with backup ID 12, created in a cluster with two database nodes having the node IDs 2 and 3, is to be restored to a cluster with four nodes. Then ndb_restore must be run twice — once for each database node in the cluster where the backup was taken. However, ndb_restore cannot always restore backups made from a cluster running one version of MySQL to a cluster running a different MySQL version. See Section 18.5.2, “Cluster Upgrade and Downgrade Compatibility”, for more information.

Note

For more rapid restoration, the data may be restored in parallel, provided that there is a sufficient number of cluster connections available. That is, when restoring to multiple nodes in parallel, you must have an [api] or [mysqld] section in the cluster config.ini file available for each concurrent ndb_restore process. However, the data files must always be applied before the logs.

Most of the options available for this program are shown in the following table:

Long Form Short Form Description Default Value
--backup-id -b Backup sequence ID 0
--backup_path None Path to backup files ./
--character-sets-dir None Specify the directory where character set information can be found None
--connect, --connectstring, or --ndb-connectstring -c or -C Set the connectstring in [nodeid=node_id;][host=]host[:port] format localhost:1186
--core-file None Write a core file in the event of an error TRUE
--debug -# Output debug log d:t:O,/tmp/ndb_restore.trace
--help or --usage -? Display help message with available options and current values, then exit [N/A]
--ndb-mgmd-host None Set the host and port in host[:port] format for the management server to connect to; this is the same as --connect, --connectstring, or --ndb-connectstring, but without a way to specify the nodeid None
--ndb-nodeid None Specify a node ID for the ndb_restore process 0
--ndb-optimized-node-selection None Optimize selection of nodes for transactions TRUE
--ndb-shm None Use shared memory connections when available FALSE
--nodeid -n Use backup files from node with the specified ID 0
--parallelism -p Set from 1 to 1024 parallel transactions to be used during the restoration process 128
--print None Print metadata, data, and log to stdout FALSE
--print_data None Print data to stdout FALSE
--print_log None Print log to stdout FALSE
--print_meta None Print metadata to stdout FALSE
--restore_data -r Restore data and logs FALSE
--restore_meta -m Restore table metadata FALSE
--version -V Output version information and exit [N/A]

Beginning with MySQL 5.0.40, several additional options are available for use with the --print_data option in generating data dumps, either to stdout, or to a file. These are similar to some of the options used with mysqldump, and are shown in the following table:

Long Form Short Form Description Default Value
--tab -T Creates dumpfiles, one per table, each named tbl_name.txt. Takes as its argument the path to the directory where the files should be saved (required; use . for the current directory). None
--fields-enclosed-by None String used to enclose all column values None
--fields-optionally-enclosed-by None String used to enclose column values containing character data (such as CHAR, VARCHAR, BINARY, TEXT, or ENUM) None
--fields-terminated-by None String used to separate column values \t (tab character)
--hex None Use hex format for binary values [N/A]
--lines-terminated-by None String used to terminate each line \n (linefeed character)
--append None When used with --tab, causes the data to be appended to existing files of the same name [N/A]

Note

If a table has no explicit primary key, then the output generated when using the --print includes the table's hidden primary key.

Beginning with MySQL 5.0.40, it is possible to restore selected databases, or to restore selected tables from a given database using the syntax shown here: 

ndb_restore other_options db_name_1 [db_name_2[, db_name_3][, ...] | tbl_name_1[, tbl_name_2][, ...]]

In other words, you can specify either of the following to be restored:

  • All tables from one or more databases

  • One or more tables from a single database

Note

ndb_restore reports both temporary and permanent errors. In the case of temporary errors, it may able to recover from them. Beginning with MySQL 5.0.29, it reports Restore successful, but encountered temporary error, please look at configuration in such cases.