I am reviewing the DR topic, but I have some doubts about the concept, I appreciate if someone supports me with any of these questions:
- Is the DR configured as passive?
- What is the general function of DR, this machine replicates the database (users, credentials and configurations) or what is the information that it synchronizes?
- How is the use of this DR machine justified for a client, so that this license is considered?
- What are the advantages of having HA (1 master + 2 Slave) against HA (1 master + 1 Slave) + DR?
1 - It will depend on the environment and disaster recovery plan. So if you have a server of senhasegura to use as a Disaster Recovery, you can set it up as passive.
Disasters Recovery is considered to be a plan to execute as an action to recover your system. And can be a server as passive, a backup pan in a remote partition of the server and a different data center, or a third server on the senhasegura cluster in another data center.
2 - The DR machine must be in the cluster of senhasegura nodes, so there will be a replication of the data (user, credentials, videos, etc.)
3 - The idea of having a server for DR is not to have just a single point to failure. For example, have two servers in a data center, and have a third in a different one. If the first data center goes down, the customer has a third server intact to restore the system.
4 - Both HA scenarios are a cluster of 3 nodes. The only difference between them is a cluster of 3 active nodes. It will be possible to access and use all the three load balancers between the three nodes.
On the environment of the two actives + DR, the access will happen only on the two server actives, and the DR will replicate.