Functions and Features

Two Architectures

DDS supports two deployment architectures: cluster and replica set, meeting requirements of different service scenarios.

Cluster
A cluster consists of three types of nodes: mongos, shard, and config. You can select the number and configuration of mongos and shard nodes to create cluster instances with different levels of service performance.

Replica set
DDS automatically builds the replica set architecture, and you can directly operate the primary and secondary nodes. DDS provides you with advanced functions such as high availability (HA) and disaster recovery (DR) switchover, and is invisible to applications.

Elastic Scaling

With the development of your services, you can change CPU and memory specifications of instances, expand storage space, and add mongos and shard nodes in real time. You are advised to perform the change during off-peak hours to avoid the impact of changes on your services.

Key Features

**Table 1** Key feature description
Features	Description
SLA	99.95%
Instant availability	You can create a DB instance on the management console and access DDS through an Elastic Cloud Server (ECS) to reduce the application response time. If you need to access a DB instance from your local devices, you can bind an elastic IP address (EIP) to the instance.
High compatibility	DDS is a document-oriented NoSQL database. It is fully compatible with MongoDB.
Visualized operation and maintenance (O&M)	You can easily perform restart, backup, and data recovery operations on instances using a graphical user interface (GUI)
Data security	A security protection system consists of VPCs, subnets, security groups, storage encryption, SSL, and DDoS protection, which is capable of defending against various malicious attacks and ensuring data security. DDS supports fine-grained permission control.
High availability	The cluster and replica set support high availability. If the primary node is faulty, the secondary node takes over services in a short time. The switchover process is invisible to applications.
Metric monitoring	DDS monitors key performance metrics of DB instances and DB engines in real time, including the CPU usage, memory usage, storage space usage, command execution frequency, delete statement execution frequency, insert statement execution frequency, and number of active connections.
Backups and restorations	DDS supports automated backup and manual backup. The maximum retention period of an automated backup is 732 days. The manual backup can be retained for a long time. DB instances can be restored using backup data.
Setting parameters	DDS allows you to manage parameter groups and modify configuration parameters on the console.