Backup and Recovery › Manual Recovery

Manual Recovery

Before You Begin

Before you attempt to manually recover the areas or files of the database, gather the available facts, such as:

1. The time of the system or transaction failure
2. Whether the failure occurred under the central version or in local mode
3. What applications were running at the time the system failed
4. Which areas of the database were in use and whether these were in update mode
5. The time of the preceding quiesce point

You can use the PRINT JOURNAL or MERGE ARCHIVE utility statements to determine the information in items 3, 4, and 5.

Locate Backup and Archive Files

After you've determined the nature of the failure, locate the most recent backup of the database and all archive journal files created since the backup.

Note: To successfully recover the database, all of the archive files must be readable. To increase the likelihood of this, you can define multiple archive files in the DMCL used to execute the ARCHIVE JOURNAL utility statement. This directs CA IDMS/DB to create multiple archive files during offload.

Determine if InDoubt Transactions Need Special Attention

Depending on the nature of the recovery operation, incomplete InDoubt transactions may need to be completed manually as part of the recovery process.

Note: For more information about dealing with InDoubt transactions during manual recovery process, see 21.4.2, “Incomplete Transactions and Manual Recovery”.

Minimize Scope of Recovery

You can limit the recovery process by recovering only the areas or files that were impacted by the failure. Areas that were available for retrieval do not have to be recovered. Depending on the nature of the failure, recovery may be restricted to an individual file. If the recovery is due to an application error, all areas updated by the application may need to be recovered to insure the logical integrity of the database. This may in turn necessitate the recovery of other areas, if another application has updated both the original and additional areas.

After You Are Done

After you recover an area or file, check the validity of the recovery by:

• Following procedures you designed to check the validity of the data; for example, by executing a report you run regularly and comparing the output to output produced before the recovery
• Verifying the structure of the database by executing the IDMSDBAN utility

Note: For more information on IDMSDBAN, see the CA IDMS Utilities Guide.

The remainder of this chapter describes manual recovery procedures under the following circumstances:

• After a warmstart fails
• I/O errors in a database file
• I/O errors in a journal file
• When journaling in local mode
• When using the database in both local mode and under the central version (mixed-mode recovery)

It also provides special considerations for data sharing environments and native VSAM files.