Procedures for Fixing Backup Verification Problems

Follow these steps when a backup fails verification. The first procedure diagnoses why a backup failed verification; the second procedure verifies an expired backup; and the third procedure verifies a backup with missing data.

To diagnose why a backup failed verification

Verify that the AC_CONFIG environment variable and the contents of the archecker configuration file are set correctly. If these variables are set incorrectly, the ON–Bar activity log displays a message.
Immediately redo the backup onto different media.
Do not reuse the original backup media because it might be bad.
Do not use any backups based on this backup. If the level-0 backup is bad, do not use the corresponding level-1 and level-2 backups.
Verify this new backup. If verification succeeds, you will be able to restore the storage spaces with confidence.
Use your storage manager to expire the backup that failed verification and then run the onsmsync utility without arguments to remove the bad backup from the sysutils and emergency boot files.
For more information on expiring data from the storage manager, see your storage-manager documentation or the IBM Informix: Storage Manager Administrator's Guide. For more information, see Using the onsmsync Utility.
If verification fails again, call Technical Support and provide them with the following information:
- Your backup tool name (ON–Bar)
- The database server online.log
- The archecker message log
- The AC_STORAGE directory that contains the bitmap of the backup and copies of important backed-up pages
If only part of the backup is corrupt, Technical Support can help you determine which portion of the backup can be restored in an emergency.
Technical Support might advise you to run oncheck options against a set of tables. (See Backups with Corrupt Pages.)

To verify an expired backup

Check the status of the backup save set on the storage manager. If the storage manager has expired the backup save set, the archecker utility cannot verify it.
Use the storage-manager commands for activating the expired backup save set. See your storage-manager documentation or the IBM Informix: Storage Manager Administrator's Guide.
Retry the backup verification: onbar -v.

To restore when a backup is missing data

Choose the date and time of an older backup than the one that just failed. To perform a point-in-time verification, use the following command:
```
onbar -v -t datetime dbspace1
```
If the older backup passes verification, perform a point-in-time physical restore using the same datetime value, then perform a log restore, as follows:
```
onbar -r -p -t datetime dbspace1
onbar -r -l
```
To prevent ON-Bar from using a backup that failed verification as part of a restore, expire the bad backup at your storage manager and then run the onsmsync utility without arguments. The onsmsync utility removes backups that are no longer held by the storage manager from the emergency boot file and the sysutils database, thereby preventing ON-Bar from attempting to use such backups.