They explain the reasoning thus[1]: Unlike some other operating systems, OpenBSD encourages users to split their disk into a number of partitions, rather than

They explain the reasoning thus[1]: Unlike some other operating systems, OpenBSD encourages users to split their disk into a number of partitions, rather than just one or two large ones. Some of the reasons for doing so are: • *Security: Some of OpenBSD's default security features rely on filesystem mount options such as nosuid, nodev, noexec or wxallowed.* • *Stability: A user or a misbehaved program can fill a filesystem with garbage if they have write permissions for it. Your critical programs, which hopefully run on a different filesystem, do not get interrupted.* • *fsck(8): You can mount partitions that you never or rarely need to write to as readonly most of the time, which will eliminate the need for a filesystem check after a crash or power interruption.* [1]: https://www.openbsd.org/faq/faq4.html#Partitioning