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Restoring a parallel backup in parallel requires anndb_restore binary from an NDB 8.0 distribution. The process is not substantially different from that outlined in the general usage section under the description of thendb_restore program, and consists of executingndb_restore twice, similarly to what is shown here:

$> ndb_restore -n 1 -b 1 -m --backup-path=path/to/backup_dir/BACKUP/BACKUP-backup_id$> ndb_restore -n 1 -b 1 -r --backup-path=path/to/backup_dir/BACKUP/BACKUP-backup_id

backup_id is the ID of the backup to be restored. In the general case, no additional special arguments are required;ndb_restore always checks for the existence of parallel subdirectories under the directory indicated by the--backup-path option and restores the metadata (serially) and then the table data (in parallel).

It is possible to restore a backup that was made using parallelism on the data nodes in serial fashion. To do this, invokendb_restore with--backup-path pointing to the subdirectories created by each LDM under the main backup directory, once to any one of the subdirectories to restore the metadata (it does not matter which one, since each subdirectory contains a complete copy of the metadata), then to each of the subdirectories in turn to restore the data. Suppose that we want to restore the backup having backup ID 100 that was taken with four LDMs, and that theBackupDataDir is/opt. To restore the metadata in this case, we can invokendb_restore like this:

$> ndb_restore -n 1 -b 1 -m --backup-path=opt/BACKUP/BACKUP-100/BACKUP-100-PART-1-OF-4

To restore the table data, executendb_restore four times, each time using one of the subdirectories in turn, as shown here:

$> ndb_restore -n 1 -b 1 -r --backup-path=opt/BACKUP/BACKUP-100/BACKUP-100-PART-1-OF-4$> ndb_restore -n 1 -b 1 -r --backup-path=opt/BACKUP/BACKUP-100/BACKUP-100-PART-2-OF-4$> ndb_restore -n 1 -b 1 -r --backup-path=opt/BACKUP/BACKUP-100/BACKUP-100-PART-3-OF-4$> ndb_restore -n 1 -b 1 -r --backup-path=opt/BACKUP/BACKUP-100/BACKUP-100-PART-4-OF-4

You can employ the same technique to restore a parallel backup to an older version of NDB Cluster (7.6 or earlier) that does not support parallel backups, using thendb_restore binary supplied with the older version of the NDB Cluster software.