Examples of Failure Scenarios

Here are some examples of failure scenarios.

Two Machine Minimally Redundant and High Availability (HA)

A Minimally Redundant database provides data redundancy. This means that data is duplicated in two or more archive areas. It does this with two TEs and two SMs, typically running on two hosts, one TE/SM combination on each host. If one TE/SM combination is gracefully shut down, the database is still available via the other TE/SM combination. However, if there is an interruption in service of one of the hosts, the database will be left in the following state:

Three Machine Setup Provides HA

The scenario described above leads to the conclusion that high availability requires at least a three machine setup. The following must be done:

Network Partition

A network partition refers to the situation where a network device fails and certain nodes in the network can no longer communicate with other nodes. If this situation occurs, two things can happen with your NuoDB domain.