Investigate gunion(8)

[probonopd]

Investigate gunion(8) by Marshall Kirk McKusick

gunion(8) tracks changes to a read-only disk using a writable disk

https://www.youtube.com/watch?v=G_skEM7jvFQ

Is this a more robust way to create an overlay filesystem

• For the Live ISO
• For testing updates and upgrades

?

https://man.freebsd.org/cgi/man.cgi?query=gunion&apropos=0&sektion=0&manpath=FreeBSD+14.0-STABLE&arch=default&format=html

Seems like this is new in FreeBSD 14.0.