Database backup and restore considerations

You can use the IBM® DB2® commands to back up and restore a DB2 database that is associated with a directory server instance. The DB2 command reduces the time that is required for the backup and restore operations, and provides the flexibility to specify the database file location.

You can use the db2 backup command that is provided by IBM DB2 to back up the DB2 database that is associated with the directory server instance. You can use the db2 restore command can be used to distribute the database across multiple disks or to move the database to another directory. An important consideration for using the db2 backup and db2 restore commands is the preservation of DB2 configuration parameters and system statistics in the backed-up database. The restored database has the same performance optimizations as the backed-up database. When you use the db2ldif, ldif2db, or bulkload commands, the DB2 system statistics and performance optimization are not maintained.

It is important to keep in mind that when you restore over an existing database, any tuning that are done on the existing database is lost. Check all the DB2 configuration parameters after you complete the database restore. If the db2 runstats command was not run before the database was backed up, tune the DB2 system statistics after the restore operation. You can use the following DB2 commands to back up and restore a database:

db2 force applications all
db2 backup  db dsrdbm01 to   directory_or_device
db2 restore db dsrdbm01 from directory_or_device replace existing

where, dsrdbm01 is the name of the directory server instance; and directory_or_device is the name of a directory or device to store the backup.

When you run the db2 restore command, you might observe file permission error. The reason for the error and steps to prevent the error are as follows:

• The DB2 instance owner might not have the required permissions to access the specified directory or file. To resolve the error, you must change the directory and file ownership to the DB2 instance owner. For example, enter the following command:

  chown dsrdbm01 file_or_device

• The backed-up database is distributed across multiple directories and those directories do not exist on the target system of the restore. Distributing the database across multiple directories can be accomplished with a redirected restore. To prevent this problem, create the same directories on the target system or run a redirected restore to specify the directories on the new system. When you create the directories, ensure that the owner of the directories is the DB2 instance owner.