A high availability environment requires at least two QueryGrid Manager instances to make sure there is no disruption to the QueryGrid functionality if one instance goes offline during a planned or unplanned outage. Teradata recommends that the QueryGrid Manager is kept in the same data center or region so that query metrics and logs generated by QueryGrid queries do not leave the region. If a region only has a small number of data source nodes, then it is okay to use QueryGrid Manager in a different region. The relationship between a data source node and QueryGrid Manager is based on the data center where each component resides. When adding new data source systems, choose the data center associated with the preferred QueryGrid Managers.