Add components

Lisa Vaysman, Daria Barysheva

In ADCM, a component means a part of a service that should be deployed on one or several cluster hosts. For example, the VictoriaMetrics service consists of such components as VictoriaMetrics Insert, VictoriaMetrics Select, and VictoriaMetrics Storage.

IMPORTANT
Initially, there are no components on any of cluster hosts. You should map components to hosts manually.

The steps for adding components to hosts are listed below:

  1. Select a cluster on the Clusters page. To do this, click a cluster name in the Name column.

    Select a cluster
    Select a cluster

  2. Open the Mapping tab on the cluster page.

    Switch to mapping service components
    Switch to mapping service components

  3. In the window that opens, map components to hosts. To assign hosts for each component, click Add hosts and select hosts in the pop-up window.

    Select hosts for a component
    Select hosts for a component
    Mandatory components

     
    Each service can have mandatory and optional components. Mandatory components are highlighted in red. The ADCM UI also displays how many mandatory components should be installed.

    Mandatory components
    Mandatory components
    CAUTION
    Without assigning a necessary number of hosts to mandatory components, the component mapping cannot be saved.

    When distributing components, it is important to consider the following:

    • Component co-location on a host. You can either install all components of an ADM cluster on a single host or distribute them among several hosts depending on your requirements. In particular, the VictoriaMetrics Insert, VictoriaMetrics Storage, and VictoriaMetrics Select components can be installed on the same host. Distributing them across several hosts provides minimal performance advantage, which is offset by higher operational complexity and resource overhead.

    • Changes to host number. Once the VictoriaMetrics Storage component has been installed, if you subsequently change the number of hosts for this component, you must restart the VictoriaMetrics Insert component via the Restart action.

    • Replication factor calculations. To ensure fault tolerance in case of a host loss, calculate the minimum number of hosts with the VictoriaMetrics Storage component installed using the following formula: 2 * N - 1 (where N is the replication factor value). For example, a replication factor of 2 requires a minimum of 3 hosts with the VictoriaMetrics Storage component.

       
      If the number of such hosts is lower than required to maintain the target replication factor, ADCM still allows cluster creation. In this case, the VictoriaMetrics Insert component writes metrics only to the available hosts running the VictoriaMetrics Storage component.

      Monitoring VictoriaMetrics Storage availability

      To monitor and identify VictoriaMetrics Storage host losses, check the following indicators on the VictoriaMetrics Insert side:

      • Internal metrics. Connection failures cause an increase in the vm_rpc_dial_errors_total, vm_rpc_connection_errors_total, or vm_rpc_handshake_errors_total counters. You can view them in a browser at http://<vminsert-host>:8480/metrics. Alternatively, connect to the VictoriaMetrics Insert host via SSH and run:

        $ curl -s http://localhost:8480/metrics | grep -E "vm_rpc_dial_errors|vm_rpc_connection_errors|vm_rpc_handshake_errors"

        Example output indicating a failed host with the VictoriaMetrics Storage component (gau-ub3):

        vm_rpc_connection_errors_total{name="vminsert", addr="gau-ub3.develop.yc.adsw.io:8400", rpc_call="metric_rows"} 1
vm_rpc_dial_errors_total{name="vminsert", addr="gau-ub3.develop.yc.adsw.io:8400", rpc_call="metric_rows"} 7718
vm_rpc_handshake_errors_total{name="vminsert", addr="gau-ub3.develop.yc.adsw.io:8400", rpc_call="metric_rows"} 1

      • VictoriaMetrics Insert logs (docker logs). Look for the cannot dial storageNode …​ connection refused error messages. To view the service logs, connect to the VictoriaMetrics Insert host via SSH and run:

        $ sudo docker logs vminsert

        Example log entry indicating a failed host with the VictoriaMetrics Storage component:

        2026-06-19T13:45:12.123Z  error  VictoriaMetrics/app/vminsert/main.go:142  cannot dial storageNode "gau-ub3.develop.yc.adsw.io:8400": dial tcp 192.168.1.10:8400: connect: connection refused

      • Network utilities. You can also connect to the VictoriaMetrics Insert hosts via SSH and use standard Linux tools (such as ss or netstat) to verify connectivity to the VictoriaMetrics Storage hosts.

  4. After component distribution is completed, click Save.

    Save mapping of components
    Save mapping of components

Starting with ADCM 2.2.0, you can use another mapping mode — by hosts. To do this, switch on the Hosts mode toggle and map components to hosts by clicking Add components for each host sequentially.

Use mapping by hosts
Use mapping by hosts
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