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- Sharded Cluster Metadata
Sharded Cluster Metadata¶
Config servers store the
metadata for a sharded cluster. The metadata reflects state and
organization of the sharded data sets and system. The metadata
includes the list of chunks on every shard and the ranges that define
the chunks. The mongos
instances cache this data and use it
to route read and write operations to shards.
Config servers store the metadata in the Config Database.
Important
Always back up the config
database before doing any
maintenance on the config server.
To access the config
database, issue the following command from the
mongo
shell:
In general, you should never edit the content of the config
database directly. The config
database contains the following
collections:
For more information on these collections and their role in sharded clusters, see Config Database. See Read and Write Operations on Config Servers for more information about reads and updates to the metadata.