Filesystems are not the most important topic in system administration—but if you configure your persistent data storage badly, doing everything else correctly won’t matter. A well–planned arrangement of disks invisibly simplifies a system administrator’s life. Ill–configured filesystems remain an annoyance until the system is wiped and rebuilt. OpenBSD is no exception. Understanding how your disks work, and how to configure them to suit the system’s workload, will make your life easier. OpenBSD includes many standard tools for disk management. Its Unix File System has been continuously used for decades and is both robust and well–understood. While it lacks features found in newer filesystems like ZFS and Btrfs, the OpenBSD developers have never been seriously interested in file system features. A file system should put data on disk. That data should be safely stored and reliably read. That’s it. Error checking? Deduplication? No. The operating system has other tools for ensuring data integrity and compactness. OpenBSD Mastery: Filesystems will take you through best practices for managing disks on OpenBSD.