Planning for an IMS system and application recovery

IMS Recovery Expert automates IMS system or application-level recovery from a System Level Backup. System recovery is performed using the System Restore and Offload panels. Application or database recovery is performed using the Application Profiles panel. Both menu options are available from the main ISPF panel.

About this task

System recovery can be a full or data only recovery. When a full system recovery is performed, IMS Recovery Expert will restore all data and log volumes. No IMS log apply recovery is performed on the restored volumes. See figure reference 3a and 3b in Planning for a local site full IMS System Level Backup with forward recovery. Performing a full systems recovery is analogous to performing a “recover to copy” when using image copies for recovery.

Figure 1 depicts the use of a System Level Backup for recovery of applications for an IMS environment.

Figure 1. Using IMS Recovery Expert to recover an application environment
This figure shows the steps that are performed to recover an IMS application from a System Level Backup. The steps include selecting backup from the metadata repository, restoring system and data volumes using fast replication if possible, parallel restore and recovery, and restarting IMS.

The following processing steps refer to Figure 1 and describe an IMS system recovery process using a IMS Recovery Expert-generated System Level Backup:

Procedure

  1. The appropriate System Level Backup metadata is selected from the metadata repository using the recovery criteria specified in the Restore System Display from the System Restore and Offload panels.
  2. IMS Recovery Expert invokes an appropriate, storage-based fast-replication process to perform the system restore process. The restore operation is performed in the storage processor without using host CPU and I/O resources.
  3. The IMS recovery processes begin after the volume restore process has started. Thus, the IMS recovery process is performed in parallel with the volume restore process to minimize overall IMS recovery time.

What to do next

Data-only recovery directs IMS Recovery Expert to restore only the data volumes from the System Level Backup (figure reference 3b, Planning for a local site full IMS System Level Backup with forward recovery). This leaves the IMS log data sets unaffected and available to use for IMS recovery processes. IMS Recovery Expert then determines and runs the recovery utilities in order to bring the databases up to the point in time specified. The recovery processes include fast data set restores and running one or more of the following utilities:

  • DBRC notifications
  • Change Accumulation Utility
  • Recover Utility
  • Rebuild Index Utility
  • Post-Recovery Image Copy Utility

These processes can take place while the storage processor is restoring the data volumes in the background. The recovery process can use a point in time or recover to current to establish the end of the recovery process. Figure 2 depicts how IMS Recovery Expert drives the various recovery processes in order to recover an application.

Figure 2. IMS Recovery Expert controlled application recovery
This figure depicts in a box how IMS Recovery Expert drives the various recovery processes in order to recover an IMS application. The box is divided such that under IMS Recovery Expert, six sub boxes detail the recovery processes that may be invoked. They include Data Set Restore, Change Accumulation Utility, Database Recovery Utility, Index Rebuilder, HALDB ILDS/Index Rebuild, and Post Recovery Image Copy Utility.

IMS application or database-level recovery is done by creating an application profile. Application profiles describe the methods and options used to recover databases or groups of related databases representing applications. Recovery profiles are created and stored in the metadata repository and can be recalled for use when an application recovery is required. The application profile specifies a recover to point as either current or a point in time. The application profile also describes which recovery resources to use by specifying whether to recover from disk, an offloaded tape, an image copy, or all available resources.

System and application recoveries can restore data and perform IMS recovery operations in parallel when recovering from a System Level Backup that resides on disk. IMS Recovery Expert will invoke an appropriate data set fast-replication process in the storage processor. While the data is flowing from the backup volume to the source IMS system to restore the data, IMS recovery processes can run in parallel with the data restoration process. The IMS Recovery Expert parallel restore and recovery process significantly reduces overall recovery time and increases application high availability.