Power

7 min · 5 sections

A home NAS stays on 24 hours a day so it can serve nothing at all between 2 and 7 in the morning. This guide covers the two ways to save electricity, noise and wear without giving up having the NAS there when you need it.

Everything is in Control Panel → Shut down and restart.

Automatic power off and power on

The NAS powers off at the time you set, on the days you set, and comes back by itself in the morning.

Before it goes, it writes into the motherboard's own clock the time it has to switch the machine on. That does not depend on the network or on anyone else: it is the same circuit that keeps the time while the machine is off.

The rule that is not up for discussion

If there is a power-on time and the alarm cannot be programmed, the NAS does NOT power off.

A NAS that powers off and never comes back leaves its owner with no data and no way to switch it on from outside. Burning one more night of electricity is, by a very wide margin, the lesser evil. When this happens the NAS says so and stays on.

It does not power off with something running either

With a backup —or an antivirus scan— running, that night's power-off is skipped and you are told. Cutting a backup in half to save a few cents of electricity is a bad trade. You can turn this off if you would rather it always powered down.

Before you trust it

Test it once with a time that is close by. Not every motherboard honours the clock alarm: the NAS checks that the ORDER is accepted, but it cannot know whether that BIOS is really going to wake up. Set it five minutes ahead, let it power off and see whether it comes back. If it does not, leave the power-on time empty and switch it on yourself (or with Wake-on-LAN).

Wake-on-LAN

This leaves the network card listening while the machine is off, so you can switch it on from your phone without waiting for the scheduled time. You need a "Wake on LAN" app on the phone and to be on the same network.

If the card does not support it, the panel says so —and also says that scheduled power-on does work, because that one does not depend on the network.

On many machines you also have to enable it in the BIOS ("Wake on LAN", "Power on by PCI-E"). The NAS does its part and does it again on every boot.

Putting the disks to sleep

Spinning disks stop on their own when nobody is using them. Less noise and less electricity on a NAS that spends the night with nobody asking it for anything.

Two things that disappoint if nobody says them:

• A busy NAS never puts them to sleep. If it records cameras, has containers writing or a virtual machine switched on, someone is always touching the disk. That is not a fault: there simply is not one quiet minute.
• Do not go below 20 minutes. Stopping and starting them all the time wears them out more than leaving them spinning, and the first access after they go to sleep takes a few seconds —which feels like "the NAS is slow" exactly when you open a folder.

SSDs are left alone: they do not "spin down" and sending them this saves nothing.

It is applied again on every boot. It is an order to the disk, not a system setting: without repeating it, sleep would work until the first power cut and then quietly stop working. The panel takes care of that.

The UPS: what happens when the power goes

A UPS is the battery that keeps the NAS on when the mains fail, just long enough for it to shut down in order instead of dropping dead. It is in Control Panel → UPS.

Shutting down is not just "power off": first the virtual machines are closed, then the containers are stopped, then everything is flushed to disk, and only then does the machine power off. That order is what keeps data from being left half-written. The screen shows, in three steps and by name, what would be closed if the cut happened right now.

Where the UPS is

The first thing you choose, because everything else follows from it:

Sharing it with the rest of the house

When you choose shared, the NAS warns the other machines over the network when the power goes. The panel shows the password —it generates it: there is nothing to make up— and the exact line to copy into each machine, inside its NUT configuration (upsmon.conf):

MONITOR nasups@192.168.1.10 1 nasred a1b2c3d4e5f6 secondary

While the UPS is shared, the NAS opens port 3493 for the local network. When you leave that mode it closes it again. That port is never opened on the router: it tells the state of the battery to whoever asks.

When the UPS is on another machine

You enter four things: the machine (network name or IP), the name the UPS has there, and the user and password that machine has set up for others. On saving, the NAS really does ask that machine about its UPS: if it does not answer, nothing is saved and it tells you why — which is nearly always the machine switched off, port 3493 closed, or the UPS name mistyped.

In this mode the NAS has no driver and no threshold of its own: the battery level that triggers the shutdown is decided by the machine the UPS is plugged into. What is identical is the shutdown: it closes its machines and containers just as if the UPS were its own.

How much power the NAS uses

On the same UPS screen, below the status, there is Power usage. It lives there and nowhere else because the UPS is the only device on the NAS that knows how much current goes through it.

• Right now: the wattage at this moment. If the UPS reports it, it says “measured by the UPS”; if it only reports the load percentage, the NAS works it out and says so — “approximate” — so nobody takes an estimate for an exact figure.
• Average over the last day: what it really uses, which is the figure worth doing sums with. On the first day it says “still measuring”: at least an hour of readings is needed.
• Per month: what that usage would cost kept up for thirty days. To see it in your currency, write the price per kWh once in the box below and save with Apply changes.

This is an estimate, not your bill: it does not include the standing charge, taxes or time-of-day rates. And what is not known is said: a zero never stands in for a missing figure. A UPS that reports neither the wattage nor the power it is rated for explains that on the same card.

Fans

In Control Panel → Shut down and restart, the Fans card shows each fan the motherboard lets you see, with its speed and its power, next to the processor temperature. Out of the box the motherboard controls them, in its automatic mode.

• "Quiet curve" hands them to the panel: slower while the device is cool and full speed from 75 °C, never below 40%. It is only offered on motherboards that obey it; on the rest, the card says why not.
• If the panel stops, can no longer read the temperature or something fails, the fans **go back to the motherboard's mode on their own**: they are never left stopped.
• If the device reports nothing about its fans, the card explains it and there is nothing to change.