# System Databases

SingleStore has several internal or "System" databases (views):

* `cluster`: Stores cluster-level metadata that is replicated to all nodes in the cluster. This includes information about nodes host/ports etc. and information about databases and database partitions). Cluster replicas (named something like: `cluster_{uint64_t}`) are created during DR (disaster recovery) cluster-to-cluster replication.
* `information.schema`: Read-only. A large set of [system tables](https://docs.singlestore.com/db/v9.1/reference/information-schema-reference.md) containing metadata about clusters and all the components within them.
* `memsql`: Stores metadata local to a given node, including which local databases exist, which local users exist, etc.

Other than `information.schema`, these databases are not intended for users. Some commands are not allowed for these databases. For example: `ATTACH`  / `DETACH DATABASE`, `BACKUP DATABASE`, `DROP DATABASE`, `REPLICATE DATABASE`, `REBALANCE PARTITIONS`, `RESTORE REDUNDANCY`.

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Modified at: July 12, 2022

Source: [/db/v9.1/reference/system-databases/](https://docs.singlestore.com/db/v9.1/reference/system-databases/)

(An index of the documentation is available at /llms.txt)