Add to ORKGThe aim of this bachelor thesis is to define the term high availability and set criteria for evaluating availability and comparing technical ways of achieving thereof with selected open source database systems. In the first part of the thesis, two definitions of high availability are presented along with several reasons for implementing highly available solutions in business information systems. They are followed by the formula for calculating availability and several metrics which can be used to compare individual highly available configurations. In the following part, general features of the selected database systems are described regarding the possibility of implementing highly available configurations and specific highly available confi...