DB Instance Types

A DB instance is the minimum management unit. Each DB instance is an independent cloud database. You can create and manage multiple databases within a DB instance. You can also access the databases in the same way you would access an independent DB instance. You can easily create or modify DB instances using the management console or HTTPS-compliant application programming interfaces (APIs).

DB instances are classified into the following types.

**Table 1** DB instance types
DB Instance Type	Description	How to Use
Single-node instances	A single-node instance contains only one primary node and there are no read replicas.	Single-node instances do not involve data synchronization between nodes and can easily ensure atomicity, consistency, isolation, and durability of transactions.
Cluster instances	A cluster instance contains one primary node and 1 to 15 read replicas. The primary node processes read and write requests, and the read replicas process only read requests.	If the primary node becomes unavailable, TaurusDB automatically fails over to a read replica.
Serverless instances	A serverless instance contains one primary node and up to seven read replicas. The primary node processes read and write requests, and the read replicas process only read requests.	Only the serverless billing mode is supported.
Multi-primary instances (OBT)	A multi-primary instance contains 2 to 63 primary nodes, with no read replicas. Such an instance can process multiple reads and writes, delivering excellent read/write performance at high concurrency.	The kernel version of a multi-primary instance must be: 2.0.63.250300, 2.0.60.241201, 2.0.60.241200, 2.0.57.240922, 2.0.57.240920, 2.0.57.240905, or 2.0.57.240900 To use multi-primary instances, submit a service ticket.