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Full System Restore

Full System Restore

This scenario assumes the following starting point:

  • The system where the restore is being performed is the same as, or identical to, the system that generated the backup.

  • All filesystems (or at least all files backed up) have been restored from the backup media and the path names at the operating system level are unchanged.

  • InterSystems IRIS is down and has not been started since the restore.

Full System Restore from External Backup or Cold Backup

If you used External Backup or Cold Backup procedures, your databases have been restored to a physically consistent state, but require at least transaction rollback to restore transactional consistently. You may also have journal files from after the time of the backup that you wish to apply before rolling back transactions. This section provides two recommended procedures, one of which you should use (depending on the details of the backup and restore you performed) for the required journal restore and transaction rollback.

If the image of the system that was restored is a snapshot of all elements of InterSystems IRIS, including the IRIS.WIJ file and journal files, from a single moment in time—that is, a crash-consistent image—and you have no newer journal files to apply, you can simply start InterSystems IRIS normally; InterSystems IRIS automatically performs journal recovery and transaction rollback. This is also true if you start InterSystems IRIS in maintenance mode, as described in Starting InterSystems IRIS for Maintenance.

Note:

The preceding recommendation applies after a crash-consistent snapshot of the entire system is restored even if normal external backup procedures (as described in External Backup and Cold Backup) were not used. In that case, the database files in the restored image may not be physically consistent, but are recovered automatically from the IRIS.WIJ file before automatic journal recovery and transaction rollback. For details on recovery, see Fundamental Data Integrity Protection and the sections that follow it.

If the restored image does not includes all elements of InterSystems IRIS — that is, the IRIS.WIJ file, the journal files, and other InterSystems IRIS files — from a single moment in time, or if you have newer journal files to apply, you must use the following procedure to perform journal restore manually, which includes transaction rollback.

Important:

This procedure assumes that the IRIS.WIJ file was backed up as part of the backup snapshot and restored along with the databases and other files and file systems, which is the recommended way to plan your backup and restore procedures. If the IRIS.WIJ file is not included in your backup, see Starting InterSystems IRIS Without Automatic WIJ and Journal Recovery for information about how to start InterSystems IRIS.

  1. Start InterSystems IRIS in maintenance mode as described in Starting InterSystems IRIS for Maintenance to perform a journal restore before users are allowed to access the system. If the instance is already running, you should stop it first and then start it again in maintenance mode.

    Note:

    If the system is down and you have auto-start configured, you may want to prevent the instance from starting automatically, so that you can start the instance in maintenance mode directly. This can only be done at the OS level and is dependent on your configuration.

  2. Restore the journals as described in Journal Restore Following Backup Restore.

  3. After the journal restore is complete, you can perform application validation or additional maintenance as needed.

  4. Restart InterSystems IRIS normally to allow users to access the system.

Full System Restore from Online Backup or Concurrent External Backup

The remainder of this section discusses the full system restore for users of Online Backup or concurrent external backup. You must perform an online backup restore to restore the databases from the backup output file. For online backup, the backup output file is written to the backup media as part of the full system backup, as described in Online Backup.

The online backup restore operation must be executed on a running instance, but the target of a full system restore cannot be running during the operation. Therefore, you must have a separate, secondary instance of InterSystems IRIS installed and available on which to execute the full system online backup restore operation. The databases being restored do not need database or namespace definitions in the secondary instance.

The secondary instance (IrisDB-2) can be installed as part of this restore procedure by running the installer and selecting an instance name and installation directory that is different from the target instance (IrisDB-1). Alternatively, to avoid this step at restore time, install the secondary “restore” instance when you decide to use the online backup strategy. This secondary instance should be shut down at all times and its installation directory backed up as part of the full system backup (that is, it would be a Cold Backup for the secondary instance). It could simply be started during a full system restore in order to run the online backup restore of the target instance.

To restore from an online backup or concurrent external backup after a full system restore:

  1. Using the secondary instance of the database (IrisDB-2), follow the instructions in Online Backup Restore Utility to:

    1. Restore the last full backup (if using concurrent external backup, the full backup was already restored externally during the filesystem restore) of the target instance.

    2. If you have done cumulative backups since the full backup, restore the last one; otherwise, continue with the next step.

    3. Restore all incremental backups done since the last cumulative backup (if there is one), or the last full backup (if there is no cumulative), in the order in which the backups were run.

  2. Using the secondary instance of the database (IrisDB-2), follow the instructions in Journal Restore Following Backup Restore.

  3. Shut down the secondary instance of the database (IrisDB-2).

  4. Start the target instance (IrisDB-1) as described in InterSystems IRIS Without Automatic WIJ and Journal Recovery. This step leaves the InterSystems IRIS database running in maintenance mode, which lets you perform application validation or additional maintenance.

  5. Restart the target instance (IrisDB-1) normally to allow users to access the system.

Important:

If you used concurrent external backup on a mirrored database on an async mirror member, you must activate the database once the mirror has started.

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