Overview of Disaster Recovery

This topic provides a brief overview of DR, discusses some considerations to keep in mind as you read this topic, and summarizes the process of managing a DR with the RMGR functions and utilities.

This topic contains the following information:

About disaster recovery

DR consists of the preparations and procedures for resuming critical data processing tasks at a remote site if a disaster (such as a fire, flood, or storm) causes a lengthy outage at the home site.

The goal is to have all necessary databases available and all necessary applications running again in the least amount of elapsed time (given the resources at the DR site), with the least loss of data, and with complete data integrity.

Scope and situation

DR is different in scope from application recovery. With DR, the amount of data to recover is massive because most or all of the databases at your site may need to be recovered. The DR site may have subtle differences from the home site, differences that may cause problems with the recovery. The business of the entire company may be halted while DR is performed. DR drills are often highly visible in the corporate environment, adding the stress of executive observation of your activities. And while no actual recovery is a relaxing, enjoyable event, a real DR can be made even more stressful by concerns about the safety of lives and property that remain at the home site.

General tools for successful disaster recovery

Successful DR involves careful planning, knowledge of your processing environment, commitment of time and resources, and a set of tools and utilities.

Your operating system, IMS, and other database management systems provide basic functions and utilities for tasks such as taking database backups, logging database changes, allocating database data sets, and performing database recoveries. The IMS Database Recovery Control (DBRC) feature helps to ensure IMS database integrity through management of information in the RECON data set.

BMC tools for disaster recovery

BMC provides enhanced tools for ensuring the success of your DR effort.

These tools provide for faster backups and recoveries, with maximum use of available resources and maximum preservation of data integrity. These tools also provide functions that are not available in other products.

The RMGR functions and utilities are ideal for helping you in the DR effort:

The Recovery Extensions feature automates management of information about additional recovery assets--especially the image copy and change accumulation data sets that you have sent offsite for DR.
Recovery Advisor detects conditions that affect recovery of IMS databases. Recovery Advisor is available only with the BMC AMI Backup and Recovery for IMS product. If you do not have BMC AMI Backup and Recovery for IMS, the Check Assets function helps to ensure that you have obtained all required image copies, logs, and change accumulation data sets.
You can build and validate groups and easily check for changes in the application (such as number of DBDs or indexes) that may have been made since the groups were defined.
The Create Recovery JCL function helps you see how many and what kind of steps are involved in the recovery.

RMGR provides two utilities designed to help you in the DR effort:

The Disaster Recovery RECON Cleanup (DRRCN) utility prepares a DBRC RECON data set for IMS startup and database recovery by closing open log records, deleting active SUBSYSTEM records, and performing other optional updates to the RECON.
The Automatic Delete/Define (DRAMS) utility captures allocation information about IMS database data sets and builds PDS members that contain TSO allocation or IDCAMS delete/define control statements.

RMGR helps you practice your DR plan at the home site. In addition to creating real JCL on a DR test system, you can practice your DR plan by creating JCL to simulate a recovery or JCL to recover to alternate databases.

Coordinated recovery

In many large data processing organizations, applications have evolved and established relationships between IMS databases, DB2 databases, and CICS/VSAM files.

Sometimes these relationships are known to the application (as in the case of a two-phase commit process), but frequently it is a more casual relationship. A transaction in one database management system may spawn a subsequent transaction in a different database management system. The transactions are tied, but the log data is not coordinated. This situation requires a coordinated recovery between IMS, DB2, and CICS/VSAM applications for both local recovery and DR.

BMC products offer exclusive technology to capture information from the database repositories and use it to derive a consistent and coordinated recovery point across these environments. For more information, see Coordinated-recovery-process.

Considerations

The focus of this information is on RMGR and IMS; disaster recovery (DR) in the overall operating system environment is mentioned briefly only as an aid to understanding of how RMGR fits into an overall plan.

This section assumes that your DR site is already prepared for execution of necessary system software and utilities (including RMGR and other BMC utilities).

For an environment that includes a product (such as RRDF) that maintains shadow copies of IMS elements, some information in this section may not apply.