Migrating the primary hard drive in OpenBSD

My web server is running on an OpenBSD VM that had to be upgraded from 7.7 to 7.8, but it turned out that the default OpenBSD drive labels created with disklabel(8)’s -A option made the /usr partition on the 16GB big drive too small to automatically update with sysupgrade(8). After having looked around a bit for some way to still do this, I first stumbled upon sysclean(8). While nice, it didn’t…