Hardware

pipeOS runs on any 64-bit x86 machine that boots UEFI: old desktops, small office boxes, a NUC. The Machines on the hardware page are the reference box below with pipeOS on them.

firmware	UEFI, Secure Boot off; the bootloader is unsigned
memory	8 GB or more. The operating system lives in RAM
media	a USB port for the live disk, or an internal SATA or NVMe drive. 8 GB or larger; the space past the image becomes /data
network	wired ethernet; the wired port is what Wake on LAN and the cluster's port LED use

No display or keyboard in normal use. The one time a keyboard is worth plugging in is the BIOS visit below.

The reference Machine

A Lenovo ThinkCentre M920q (type 10RR): Intel Core i5, eighth generation, six cores; 32 GB of RAM; Intel I219 gigabit ethernet; hardware video encode on the Intel GPU, which carries 1080p60 streaming.

Machines in a cluster carry one more part: a 10 GbE SFP+ card on the chassis riser, for the switch that joins them. A cluster assembled from single Machines runs on the on-board gigabit, the same but slower. A magic packet does not wake the box through the SFP+ port, so a Machine that should answer Wake keeps its on-board port cabled too.

The BIOS: wake and power loss

Two firmware switches decide whether a Machine that is off can come back on its own. The operating system cannot flip them. Power on with a keyboard attached and press F1 at the Lenovo splash:

Wake on LAN	Power → Automatic Power On → Wake on LAN → Automatic (or Primary: only the on-board port). Disabled is the factory value on some batches. Some revisions also carry Advanced → Power → Wake on LAN from S5; it must not be Disabled
After Power Loss	Power → After Power Loss → Power On: a box that lost mains comes back without waiting for a packet

F10 saves. The NIC side needs nothing from you: every boot arms the port (ethtool eth0 | grep Wake-on should read Wake-on: g), and the boot report says when it could not.

Wake works from soft-off; a box whose mains was pulled wakes only if After Power Loss is Power On. The packet is a broadcast on the local segment from any Machine that has ever seen the target. The drill: shut a Machine down, watch it turn grey on a sibling's Network view within about forty seconds, press Wake; back within a minute, or the BIOS side is off.

The watchdog

The M920q's chipset has a hardware timer. Every boot arms it for 60 seconds and a service pets it every 20. There is no health probe on purpose: a busy box is not a hung box, and a probe's false positives are reboots mid-write. A hung kernel or dead userspace stops the petting, the chipset resets the box, and the next boot report names it: kernel panic: the watchdog rebooted us, or watchdog or power loss for an unclean stop, because the chipset cannot tell the two apart.

$ pipeos watchdog status
$ pipeos watchdog kernel        # armed (the default)
$ pipeos watchdog off

A virtual machine has no such timer; the report says nothing to arm.

Next

The live disk, then first boot.