Any partition that uses a non-FFS filesystem is foreign to OpenBSD. Although OpenBSD can access many foreign filesystems, don’t expect it to be seamless.
Support for some filesystems is incomplete. For example, you can mount Microsoft NTFS partitions only as read-only. Other filesystems don’t support the full range of OpenBSD commands. Because FAT filesystems don’t have any concept of file ownership or permissions, commands like
chown won’t change anything on the disk.
Each supported filesystem has its own mount program to handle the vagaries of that filesystem. To simplify your life,
mount can usually recognize supported filesystems from the on-disk format and call the correct mount program as needed. To mount a ...