An untethered or uncompressed diskless boot downloaded the root image
only from the deployment server and retried it forever when that server
failed. Try the other managers that answered discovery as well, as the
tethered urlmount already does.
urlmount limits each small range request to 10 seconds, but the single
whole-image download cannot take a total limit. Give up on a connect
after 10 seconds and on a transfer that stalls for 30 seconds instead,
so a hung server moves on to the next one.
The initramfs has a reduced set of modules to boot and then
in diskless mode hands over to the 'real' OS for all userspace
to use the more substantial root filesystem with all of the modules.
However one exception is kernel module autoload, which induces modprobe
to run in the initial mount namespace unconditionally.
Thus, preserve the ramfs drivers (just in case) but have the autoloading
pivot
to the normal root filesystem to get the full complement of modules.
Markus Hilger
Jarrod Johnson