Verifying Your Database Server Configuration

During a cold restore, you cannot reinitialize shared memory, add chunks, or change tape devices. Thus, when you begin the restore, the current database server configuration must remain compatible with, and accommodate, all parameter values assigned after the time of the most recent backup.

For guidance, use the copies of the configuration file that you create at the time of each backup. However, do not set all current parameters to the same values as were recorded at the last backup. Pay attention to the following three groups of parameters:

• Shared-memory parameters
• Mirroring parameters
• Device parameters

Setting Shared-Memory Parameters to Maximum Assigned Value

Make sure that you set your current shared-memory parameters to the maximum value assigned after the level-0 backup. For example, if you decrease the value of USERTHREADS from 45 to 30 sometime after the level-0 backup, you must begin the restore with USERTHREADS set at 45, and not at 30, even though the configuration file copy for the last backup could register the value of USERTHREADS set at 30. (When you do not possess a record of the maximum value of USERTHREADS after the level-0 backup, set the value as high as you think necessary. You could reassign values to BUFFERPOOL, LOCKS, and TBLSPACES as well because the minimum values for these three parameters are based on the value of USERTHREADS.)

Setting Mirroring Configuration to Level-0 Backup State

Verify that your current mirroring configuration matches the configuration that was in effect at the time of the last level-0 backup. Because it is recommended that you create a level-0 backup after each change in your mirroring configuration, this creates no problems. The most critical parameters are the mirroring parameters that appear in the ONCONFIG configuration file, MIRRORPATH and MIRROROFFSET.

Ensuring That Needed Devices Are Available

Verify that the raw devices or files that you used for storage (of the storage spaces being restored) after the level-0 backup are available.

For example, if you drop a dbspace or mirroring for a dbspace after your level-0 backup, you must make the dbspace or mirror chunk device available to the database server when you begin the restore. When the database server attempts to write to the chunk and cannot find it, the restore does not complete. Similarly, if you add a chunk after your last backup, you must make the chunk device available to the database server when it begins to roll forward the logical logs.