smartmontools's periodic scan should skip vtbd devices. See the Phabricator link for the patch.
A commit references this bug: Author: asomers Date: Sun May 3 13:22:51 UTC 2020 New revision: 533779 URL: https://svnweb.freebsd.org/changeset/ports/533779 Log: sysutils/smartmontools: skip virtio disk devices during periodic scan PR: 245935 Reviewed by: samm Approved by: samm (maintainer) Sponsored by: Axcient Differential Revision: https://reviews.freebsd.org/D24191 Changes: head/sysutils/smartmontools/Makefile head/sysutils/smartmontools/files/smart.in