Resource relationships in Managed Service for MySQL®
The main entity used in Managed Service for MySQL® is a cluster.
Each cluster consists of one or more DB hosts, which are virtual machines with DBMS servers deployed. Cluster hosts may reside in different availability zones and even different availability regions. You can learn more about Yandex Cloud availability zones in Platform overview.
A cluster with two or more hosts is natively highly available because hosts can step in for one another as the cluster’s primary replica. To learn more about how the number of hosts affects cluster availability, see this section.
The minimum number of hosts in a cluster depends on the selected disk type. The default cluster configuration offered in the management console includes two hosts.
Warning
We do not recommend creating a cluster having a single host. While being cheaper, such a cluster will not ensure high availability.
VMs for cluster hosts can be hosted on:
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Regular Yandex Cloud hosts.
These are physical servers for hosting cluster VMs. They are randomly selected from a pool of available hosts that meet the selected cluster configuration.
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Dedicated Yandex Cloud hosts.
These are physical servers reserved exclusively for your VMs. VMs on dedicated hosts have all features of regular VMs; additionally, they are physically isolated from other users' VMs.
Dedicated hosts are selected from dedicated host groups specified when creating a cluster.
For more information, see Dedicated host.
When creating a cluster, specify:
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Host class: VM template for deploying the cluster hosts. For a list of available host classes and their specs, see Host classes.
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Environment: Environment where the cluster will be deployed:
PRODUCTION: For stable versions of your applications.PRESTABLE: For testing purposes. The prestable environment is similar to the production environment and likewise covered by an SLA, but it is the first to get new features, improvements, and bug fixes. In the prestable environment, you can test new versions for compatibility with your application.
A cluster created in a folder can be accessed by all VMs connected to the same cloud network. For more information about networking, see the Virtual Private Cloud documentation.
Alert
The service can automatically access the system and diagnostic information of your databases to build monitoring charts and maintain your cluster health. The service never queries or uses the data you saved to the database.
Be mindful of what is what is controlled by the service, and what by the Yandex Cloud customer. Understanding these control zones will help you use your cloud resources effectively and avoid potential database-related problems. For more information, see Zones of control between managed database (MDB) service users and Yandex Cloud.