@dmcnutt
USB disks show up here just like other disks in "df", so that's normal.
/dev/dm-0 is most likely an encrypted partition. /boot cannot be in an encrypted partition because you need it for decryption. If the disk was just one big encrypted partition, you'd need to boot on a USB stick or something in order to decrypt it. If you install ubuntu on a disk using disk encryption (for example ext4), then you don't need to separate /boot on a separate partition.
@dmcnutt
USB disks show up here just like other disks in "df", so that's normal.
/dev/dm-0 is most likely an encrypted partition. /boot cannot be in an encrypted partition because you need it for decryption. If the disk was just one big encrypted partition, you'd need to boot on a USB stick or something in order to decrypt it. If you install ubuntu on a disk using disk encryption (for example ext4), then you don't need to separate /boot on a separate partition.