I was looking for a NetBSD equivilent to devd on FreeBSD to react to disk changes. At work we inject configuration into virtual machines using a separate disk, which can be live ejected and attached.

This mailing list post by Martin Husemann entry from 2012 suggests I should check out devpubd. From the man(8) page:

devpubd - device publish daemon for automatic device node creation … devpubd listens on drvctl(4) for new devices and creates their device nodes using MAKEDEV(8)

Unless anyone can think of something else I should try, I’ll check this out. Also, that desktop background took me back.