Forensic implications of stacked file systems

While file system analysis is a cornerstone of forensic investigations and has been extensively studied, certain file system classes have not yet been thoroughly examined from a forensic perspective. Stacked file systems, which use an underlying file system for data storage instead of a volume, are a prominent example. With the growth of cloud infrastructure and big data, it is increasingly likely that investigators will encounter distributed stacked file systems, such as MooseFS and the Hadoop File System, that employ this architecture. However, current standard models and tools for file system analysis fall short of addressing the complexities of stacked file systems. This paper highlights the forensic challenges and implications associated with stacked file systems, discussing their unique characteristics in the context of forensic analyses. We provide insights through three analyses of different stacked file systems, illustrating their operational details and emphasizing the necessity of understanding this file system category during forensic investigations. For this purpose, we present general considerations that must be made when dealing with the analysis of stacked file systems.