Because of the time needed for this check and the possible contention that the check can cause, schedule this check for times when activity is at its lowest. It is recommended that you perform this check just before you create a level-0 dbspace backup.
Run the onutil commands shown in Table 28 as part of the consistency check.
| Type of Validation | Command |
|---|---|
| Data | onutil CHECK DATA IN DATABASE dbname |
| Extents | onutil CHECK SPACE |
| Indexes | onutil CHECK INDEX WITH
DATA
IN DATABASE dbname or onutil CHECK ALLOCATION INFO |
| Logical logs | onutil CHECK LOGS |
| Reserved pages | onutil CHECK RESERVED |
| System catalog tables | onutil CHECK CATALOGS |
You can run each of these commands while the database server is in online mode. For information about how each command locks objects as it checks them and which users can perform validations, see onutil in the IBM Informix: Administrator's Reference.
In most cases, if one or more of these validation procedures detects an error, the solution is to restore the database from a dbspace backup. However, the source of the error might also be your hardware or operating system.
To validate data pages, use the onutil CHECK DATA command.
If data-page validation detects errors, try to unload the data from the specified table, drop the table, re-create the table, and reload the data. For information about loading and unloading data, see the IBM Informix: Migration Guide. If this procedure does not succeed, perform a data restore from a storage-space backup.
To validate extents in every database, use the onutil CHECK SPACE command.
Extents must not overlap. If this command detects errors, perform a data restore from a storage-space backup.
To validate indexes on each of the tables in the database, use the onutil CHECK INDEX WITH DATA command.
If this command detects errors, drop and re-create the affected index.
To validate logical logs, use the onutil CHECK LOGS command.
To validate reserved pages, use the onutil CHECK RESERVED command.
Reserved pages are pages that reside at the beginning of the initial chunk of the root dbspace. These pages contain the primary database server overhead information. If this command detects errors, perform a data restore from storage-space backup.
This command might provide warnings. In most cases, these warnings call your attention to situations of which you are already aware.
To validate system catalog tables, use the onutil CHECK CATALOGS command.
Each database contains its own system catalog, which contains information about the database tables, columns, indexes, views, constraints, stored procedures, and privileges.
If a warning appears when validation completes, its only purpose is to alert you that no records of a specific type were found. These warnings do not indicate any problem with your data, your system catalog, or even your database design. For example, the following warning might appear if you validate system catalog tables for a database that has no synonyms defined for any table:
WARNING: No syssyntable records found.
This message indicates only that no synonym exists for any table; that is, the system catalog contains no records in the table syssyntable.
However, if you receive an error message when you validate system catalog tables, the situation is quite different. Contact IBM Technical Support immediately.
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