Analyzing data set isolation

If the intended usage of a System Level Backup requires data set isolation, then the physical location of the data sets and the user catalogs for these data sets must be examined.

If the use for the System Level Backup does not require data set isolation, such as Application or Database Recovery only, then you can skip this section.

The requirement to have data isolated for some restore operations is because IMS Recovery Expert invokes a volume level restore for certain operations. When a volume is restored, all of the data sets will be restored as they existed at the time the SLB was created. Considerations must be made for non-IMS data sets that might reside on the volumes being restored. Also, the user catalogs must reflect the data sets on the volumes being restored.

IMS Recovery Expert provides an IMS System Analysis and Configuration function that will help you in analyzing the data set placement for all of the data sets in an IMS environment (see (Optional) Analyzing IMS data set placement for System Level Backup validation). The IMS System Analysis and Configuration function will also report on what type of restores and recoveries are allowed with the current configuration.

The following table summarizes data set isolation requirements based on a System Level Backup's usage:

Table 1. Data set isolation requirements
System Level Backup usage Data set isolation requirements Considerations
Local site full system restore with forward recovery
  1. User catalogs for all IMS data sets need to be included in the System Level Backup.
  2. Log and RECON data sets and their associated user catalogs need to be isolated from database data sets and their associated user catalogs.
  1. Non-IMS data sets may be restored.
  2. User catalogs should not contain non-IMS data sets if the data sets are not on volumes being backed up.
Local site full system restore with no forward recovery User catalogs for all IMS data sets need to be included in the System Level Backup.
  1. Non-IMS data sets may be restored.
  2. User catalogs should not contain non-IMS data sets.
Application or database recovery User catalogs for the application or database data sets need to be included in the System Level Backup. Only SCOPE=Data is needed.
Disaster, or remote site recovery User catalogs for all IMS data sets need to be included in the System Level Backup.
  1. Non-IMS data sets may be restored.
  2. Partial System Level Backup cannot be used.

The most stringent data set isolation requirements are required when you are using a System Level Backup to do a local site full system restore with forward recovery. To ensure complete and accurate system restoration, follow these recommendations for the IMS system setup:

  • The user catalog(s) for the IMS log and RECON data sets should be separate from the user catalog(s) for IMS databases and indexes, and should not reside on the same volume(s) as any other IMS databases or IMS database catalog(s).
  • The IMS RECON, active log, and archive log data sets should reside on separate volumes from the IMS database data.

These requirements ensure that your IMS database and log data are contained on separate sets of volumes. When you restore the volumes, the user catalogs will be restored and will reflect the data and log locations as they were at the time of the backup as shown in Planning for a local site full IMS System Level Backup with forward recovery.