:original_name: en-us_topic_introduction.html

.. _en-us_topic_introduction:

What Is DDS?
============

Document Database Service (DDS) is a high availability DBaaS, which provides a secure, reliable and scalable solution, compatible with MongoDB community version 4.0.3 as baseline version.It provides functions such as one-click deployment, elastic capacity expansion, disaster recovery, backup, restoration, monitoring, and alarm reporting.

DDS has the following features:

-  DDS automatically establishes the three-node replica set architecture. It supports fast deployment, high availability (HA) data storage, data redundancy, and failover.
-  DDS provides sharded cluster instances comprised of a config node paired with multiple shards and mongos nodes. These clusters can be easily scaled up to enhance read and write performance.
-  DDS lets you back up or restore a database from the management console in just a few clicks.
-  DDS provides performance metrics and you can configure alarm notifications to make it easier to keep abreast of instance statuses.

For details about the compatible DB engines and versions, see :ref:`Database Engine and Version <dds_01_0014>`.