A dbspace can be flagged as a read-only dbspace (also known as a static dbspace) to inform the server that any data stored in the dbspace will not be modified. Attempts to modify such data will result in ISAM error 21501.
Read-only dbspaces are particularly useful in data warehousing environments, which typically contain large amounts of static data. In particular, flagging dbspaces containing static data as read-only dbspaces can greatly improve the performance of backup and restore. Because the contents of read-only dbspaces do not change, such dbspaces do not need to be backed up as frequently as dbspaces containing modifiable data. The ON-Bar backup utility can be configured to avoid archiving read-only dbspaces that have already been backed up, while still backing up other dbspaces in the system.
If your data warehouse contains large amounts of static data, place the read-only data in dbspaces separate from those you want to continue to modify. After you have loaded the data in your data warehouse, bring the server to quiescent mode and change the status of dbspaces containing data that will no longer be modified to read-only.
Use the onutil ALTER DBSPACE STATIC command to change a non-critical dbspace to read-only status. The server must be in quiescent mode to use this command.
Use the onutil ALTER DBSPACE OPERATIONAL command to change a dbspace that you have previously flagged as read-only (static) back to read-write (operational) mode.
For more information on the use of the ALTER DBSPACE STATIC and ALTER DBSPACE OPERATIONAL commands, see the IBM Informix: Extended Parallel Server Administrator's Reference.
For more information on the ON-Bar backup utility, see the IBM Informix: Backup and Restore Guide.
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