The rise of cyber crime and the growing number of anti-forensic tools demand more research on combating anti-forensics. A prominent anti-forensic paradigm is the hiding of data at different abstraction layers, including the filesystem layer. This chapter evaluates various techniques for hiding data in the ext4 filesystem, which is commonly used by Android devices. The evaluation uses the capacity and detection rating metrics. Capacity reflects the quantity of data that can be concealed using a hiding technique. Detection rating is the difficulty of finding the concealed artifacts; specifically, the amount of effort required to discover the artifacts. Well-known data hiding techniques as well as new techniques proposed in this chapter are evaluated.