# Maintenance mode

In this mode, the node is not reachable from the outside, i.e.

> * it refuses all incoming RPC connections,
> * it does not join the cluster, thus
>   * all operations that need synchronizing with other nodes are disabled (e.g. schema changes),
>   * all cluster-wide operations are disabled for this node (e.g. repair),
>   * other nodes see this node as dead,
>   * cannot read or write data from/to other nodes,
> * it does not open Alternator transport ports and the TCP CQL port.

The only way to make CQL queries is to use [the maintenance socket](https://docs.scylladb.com/manual/master/operating-scylla/admin-tools/maintenance-socket.md). The node serves only local data.

To start the node in maintenance mode, use the –maintenance-mode true flag or set maintenance_mode: true in the configuration file.

REST API works as usual, but some routes are disabled:

> * authorization_cache
> * failure_detector
> * hinted_hand_off_manager