How will you create a Disaster Recovery Plan and set up failover in MS SQL Server and PostgreSQL?

Disaster Recovery Plan (DRP) is a document and a set of procedures that ensure the restoration of database operation after a failure.

Creating a DRP and configuring failover in MS SQL Server:

1. Backup: Regular full and differential backups, as well as transaction log backups.
2. Always On Availability Groups: Setting up availability groups for automatic failover to a secondary server in case of failure.
3. Failover Cluster Instances (FCI): Using Windows Server clusters to ensure high availability.
4. Testing: Regular testing of recovery from backups and failover switching.

In PostgreSQL:

1. Backup: Using pg_basebackup and WAL archiving to create exact copies.
2. Streaming Replication: Setting up streaming replication to create hot standby servers.
3. Failover: Using tools like Patroni or repmgr for automatic failover.
4. Testing: Verifying recovery from backups and correctness of failover.

In both cases, it is important to document procedures, regularly check backups, and practice recovery scenarios to minimize downtime and data loss.