The configuration file describes the physical configuration of a VoltDB database cluster at runtime, including the number of sites per hosts and K-safety value, among other things. This appendix describes the syntax for each component within the configuration file.
The configuration file is a fully-conformant XML file. If you are unfamiliar with XML, see Section E.1, “Understanding XML Syntax” for a brief explanation of XML syntax.
The configuration file is a fully-conformant XML file. XML files consist of a series of nested elements identified by beginning and ending "tags". The beginning tag is the element name enclosed in angle brackets and the ending tag is the same except that the element name is preceded by a slash. For example:
<deployment> <cluster> </cluster> </deployment>
Elements can be nested. In the preceding example
cluster is a child of the element
Elements can also have attributes that are specified within the starting tag by the attribute name, an equals sign, and its value enclosed in single or double quotes. In the following example the hostcount and sitesperhost attributes of the cluster element are assigned values of "2" and "4", respectively.
<deployment> <cluster hostcount="2" sitesperhost="4"> </cluster> </deployment>
Finally, as a shorthand, elements that do not contain any children can be entered without an ending tag by adding the
slash to the end of the initial tag. In the following example, the
heartbeat tags use this form of shorthand:
<deployment> <cluster hostcount="2" sitesperhost="4"/> <heartbeat timeout="10"/> </deployment>
For complete information about the XML standard and XML syntax, see the official XML site at