What Happens During a Restore Operation?

The database server administrator or operator uses ON–Bar to request a restore operation. When the ISM server receives a restore request from ON–Bar, ISM searches the ISM catalog to identify the required storage volumes. When ISM recovers data, ISM requests a specific storage volume by name. To fulfill this request, mount the appropriate storage volume on one of the storage devices that is attached to the ISM server.

Figure 3 illustrates how data and requests move between ON–Bar, the ISM server, and the database server through XBSA during a restore operation. Restore requests are processed in the following sequence:

1. The user uses ON–Bar to start a restore operation.
2. ON–Bar determines what data needs to be restored.
3. ON–Bar connects to the ISM server.
4. The ISM server searches the ISM catalog for specific restore objects that ON–Bar requests. ISM maps each restore object to its offset in a save set.
5. ON–Bar retrieves the data from the ISM server and passes it to the Informix database server, object by object.
6. The database server writes the data to the proper storage spaces or logical logs.
7. After the restore operation finishes, ON–Bar disconnects from ISM.
   Figure 3. Data Movement During an ON-Bar Restore