Mode groups

Modes are grouped into logical collections called Mode Groups. Within a mode group, only one mode can be active at a time.

Note: No exclusivity is enforced between modes within different mode groups.

Modes are treated as mutually exclusive based on the ownership privilege. Only one system can ever be the designated owner of a dataset in any given operating mode. Thus, mode groups are useful in defining which modes are mutually exclusive, and which modes are independent.

Consider the following scenario with a primary and two backup systems.

Any modes that define the relationship between the primary and the first backup system may belong to one mode group -- and therefore only one of these modes may be active. The modes defining the relationship between the primary and the second backup system may belong to a second mode group.

In this scenario the PRI/BAC1 relationship is independent of the PRI/BAC2 relationship. In this configuration style, it is ensured that the relationship between the primary and the first backup system is independent of the primary and the second backup system. A Mode Switch can occur to one mode group without impacting the other.

The mode groups are not represented by an entity in the physical data model, although a column of the doas_mode table identifies the mode group of each mode and another column identifies the active mode. In other words, the mode group is just a string within each of the doas_mode records. To create a new mode group, you simply create a new unique string within this field. To associate two mode records together within the same mode group, enter the same string within the Mode Group field for these two records.