The Volt Management Center (VMC) is a web-based console for monitoring and managing VoltDB databases. The console includes panels for viewing and editing the database configuration and schema, as well as tabs for monitoring real-time performance of transactions, import and export activities, and Active(N) replication. There is even a tab for executing ad hoc queries against the database.

On bare metal systems, VMC currently starts automatically as part of the database server. However, it is also available as a standalone service. And on Kubernetes, VMC is started as a standalone service by default. Use of the standalone service is recommended for two primary reasons:

The VMC service actually consists of two separate components:

The following sections explain how to install and run the standalone VMC service on bare metal systems.

The only requirement for installing and running the VMC service is that the system you run it on must include Java runtime version 8.0, 11.0 or later. VMC comes as a zipped tarball that you can find where you get your Volt Active Data server software. The tarball is named voltdb-vmc-xx.x.x.tar.gz, where "xx..x.x" is the version number.

Download and unpack the file to create a directory with the VMC service executables and command line. For example, to install version 13.2.0 of VMC in your top-level directory and rename the directory to voltvmc, use the following commands:

$ tar -zxvf voltdb-vmc-13.2.0.tar.gz -C $HOME
$ cd ~
$ mv voltdb-vmc-13.2.0 voltvmc

Note that, although the VMC service is versioned, it does not need to be updated or match the version of the database servers it services. Any VMC service can interoperate with any version V13.0 or later of the VoltDB server software.

Once VMC is installed, you can invoke the service in either one of two ways:

Using the Linux Executable

For most Linux systems, including Ubuntu and Red Hat, VMC comes as a precompiled Linux executable with a command line interface. You can invoke the executable in the bin subfolder where VMC is installed. For example:

$ ~/voltvmc/bin/vmc

Or you can add the bin subfolder to your path and to your login script so you can use the vmc command directly:

$ export PATH="$PATH:$HOME/voltvmc/bin"
$ vmc

Using the Java JAR File

For other operating systems, including other Linux variants or platforms such as Microsoft Windows, you can run VMC from the included Java JAR file. For example:

$ java -jar ~/voltvmc/libvmc/volt-vmc-svc.jar

When you start the VMC service without any qualifiers, it assumes it is connecting to a database process on the current node using the default ports and default settings (for example, no TLS/SSL configuration). In most cases you want to connect to a database on a different node, possibly using non-default ports and/or configurations. So at a minimum, you will usually want to specify at least one database server to connect to. For example, assuming the bin directory has been added to your path:

$ vmc --server=dbsvr1.myorg.com

You can specify multiple servers using a comma-separated list. However, even if you only specify one, the VMC service uses the topology aware Java client to identify and connect to all the servers in the cluster and direct requests appropriately. The next section describes all of the arguments you can use to customize the connection between the VMC service and the database servers.

The vmc command starts an HTML server process that users can connect to for accessing the web-based management console or processing transactions through the JSON HTTP API.

vmc  [argument...]