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DDS UMN Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com> Co-authored-by: proposalbot <proposalbot@otc-service.com> Co-committed-by: proposalbot <proposalbot@otc-service.com>
40 lines
1.2 KiB
ReStructuredText
40 lines
1.2 KiB
ReStructuredText
:original_name: dds_01_0002.html
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.. _dds_01_0002:
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Cluster
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=======
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DDS cluster instances consist of mongos, config, and shard nodes. The following diagram shows the node relationships.
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.. figure:: /_static/images/en-us_image_0284275219.png
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:alt: **Figure 1** Diagram of node relationships
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**Figure 1** Diagram of node relationships
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mongos
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------
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A mongos is a router for reading and writing data, providing a unified interface for accessing DB instances.
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- Each DB instance has 2 to 16 mongos. You can specify the quantity.
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- A mongos reads configuration settings from configs and allocates read and write requests to shards. You can connect to a mongos directly.
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config
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------
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A config stores configuration settings for DB instances and consists of one replica set.
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- The availability of a config is the prerequisite to deploying a DB instance or modifying the instance information.
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- You cannot connect to a config directly.
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shard
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-----
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In the cluster instance, shards are used to store user data.
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- Each DB instance has 2 to 16 shards. You can specify the quantity.
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- Each shard is deployed as a replica set to ensure data redundancy and high reliability.
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- You cannot connect to a shard directly.
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