MongoDB Documentation, Release 3.0.4 multiple shards 12 to fulfill these queries. Sharding operates on the collection level. You can shard multiple collections within a database or have multiple databases with sharding enabled. 13 However, in production deployments, some databases and collections will use sharding, while other databases and collections will only reside on a single shard. Regardless of the data architecture of your sharded cluster , ensure that all queries and operations use the mongos router to access the data cluster. Use the mongos even for operations that do not impact the sharded data. MongoDB supports tagging a range of shard key values to associate that range with a shard or group of shards. Those shards receive all inserts within the tagged range. The balancer obeys tagged range associations, which enables the following deployment patterns: This document describes the behavior, operation, and use of tag aware sharding in MongoDB deployments. Chapter 10. Sharding 682 12 mongos will route some queries, even some that include the shard key, to all shards, if needed. 13 As you configure sharding, you will use the enableSharding command to enable sharding for a database. This simply makes it possible to use the shardCollection command on a collection within that database. • isolate a specific subset of data on a specific set of shards. • ensure that the most relevant data reside on shards that are geographically closest to the application servers. Tag Aware Sharding Sharded and Non-Sharded Data