A.4. Path Configuration Options

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A.4. Path Configuration Options

The running database uses a number of disk locations to store information associated with runtime features, such as export, network partition detection, and snapshots. You can control which paths are used for these disk-based activities. The path configuration options include:

  • VoltDB root

  • Snapshots path

  • Export overflow path

  • Command log path

  • Command log snapshots path

A.4.1. VoltDB Root

VoltDB defines a root directory for any disk-based activity which is required at runtime. This directory also serves as a root for all other path definitions that take the default or use a relative path specification.

By default, the VoltDB root is the directory voltdbroot created as a subfolder in the current working directory for the process that starts the VoltDB server process. (If the subfolder does not exist, VoltDB creates it on startup.) You can specify an alternate root in the deployment file using the <voltdbroot> element. However, if you explicitly name the root directory in the deployment file, the directory must exist or the database server cannot start. See the section on "Configuring Paths for Runtime Features" in the Using VoltDB manual for details.

When using the VoltDB Enterprise Manager, the VoltDB root directory is defined implicitly by the destination directory. You define the destination directory when you create the database. The VoltDB root becomes a subfolder of the destination directory, where the subfolder name is the same as the database ID of the current database. So, for example, if the destination directory is /opt/voltdb and the database ID is 12345, the resulting VoltDB root directory is /opt/voltdb/12345.

A.4.2. Snapshots Path

The snapshots path specifies where automated and network partition snapshots are stored. The default snapshots path is the "snapshots" subfolder of the VoltDB root directory. You can specify an alternate path for snapshots using the <snapshots> child element of the <paths> tag in the deployment file.

A.4.3. Export Overflow Path

The export overflow path specifies where overflow data is stored if the export queue gets too large. The default export overflow path is the "export_overflow" subfolder of the VoltDB root directory. You can specify an alternate path using the <exportoverflow> child element of the <paths> tag in the deployment file.

See the chapter on "Exporting Live Data" in the Using VoltDB manual for more information on export overflow.

A.4.4. Command Log Path

The command log path specifies where the command logs are stored when command logging is enabled. The default command log path is the "command_log" subfolder of the VoltDB root directory. However, for production use, it is strongly recommended that the command logs be written to a dedicated device, not the same device used for snapshotting or export overflow. You can specify an alternate path using the <commandlog> child element of the <paths> tag in the deployment file.

See the chapter on "Command Logging and Recovery" in the Using VoltDB manual for more information on command logging.

A.4.5. Command Log Snapshots Path

The command log snapshots path specifies where the snapshots created by command logging are stored. The default path is the "command_log_snapshot" subfolder of the VoltDB root directory. (Note that command log snapshots are stored separately from automated snapshots.) You can specify an alternate path using the <commandlogsnapshot> child element of the <paths> tag in the deployment file.

See the chapter on "Command Logging and Recovery" in the Using VoltDB manual for more information on command logging.