This paper explores the significance of schools' data infrastructures as a site of institutional power and (re)configuration. Using 'infrastructure studies' as a theoretical framework and drawing on in-depth studies of three contrasting Australian secondary schools, the paper takes a holistic look at schools' data infrastructures. In contrast to the notion of the 'platformatised' school, the paper details the ad hoc and compromised ways that these school data infrastructures have developed -- highlighting a number of underlying sociotechnical conditions that lead to an ongoing process of data infrastructuring. These include issues of limited technical interoperability and differences between educational requirements and commercially-led designs. Also apparent is the disjuncture between the imagined benefits of institutional data use and the ongoing maintenance and repair required to make the infrastructures function. Taking an institutional perspective, the paper explores why digital technologies continue to complicate (rather than simplify) school processes and practices.