Relationship between service resources
The main entity used in Managed Service for ClickHouse is a database cluster.
Each cluster consists of one or more database hosts, which are virtual machines with DBMS servers deployed on them. Cluster hosts may reside in different availability zones and even different availability regions. Learn more about Yandex.Cloud geography.
A cluster consisting of multiple hosts has automatic failover, because the hosts can take over each other's functions as the cluster's primary replica.
A single-host cluster doesn't guarantee fault tolerance. To add replicas, first add the ZooKeeper hosts that manage replication and query distribution across the cluster hosts.
When creating a cluster or shard, specify the host class, which is a template of virtual machine characteristics for the hosts deployed. For a list of available host classes and their characteristics, see Host classes.
A database cluster created in a folder can be accessed by all VMs connected to the same cloud network. Learn more about networking.
The service may automatically request system and diagnostic data about your databases to draw monitoring graphs and maintain the operability of the cluster. The service never requests or uses the data you inserted into databases yourself.