Performing automated shutdown during a power failure using a USB-UPS with NUT - XCP-ng 8.2

lknite

@Hannes_5253 awesome! Thank you for this posting, it's helping me to get a nut client installed. Note for folks coming across this later I needed to use the following to install the nut-client:

yum -y install nut-client --enablerepo=epel

It would be cool if xcp-ng came pre-installed with nut-client and a default configuration that shuts down the xen server & turns off the ups after it finishes shutting down... similar to how truenas has a service which can be enabled to do so. You'd have to configure it of course, with the nut server to monitor, credentials, and some other options such as whether to actually powerdown the ups after shutting down or not, but maybe through a nice gui after turning it on. Seems like everyone should be using this setup ... just a matter of time till they are ready to.

Another reason this would be nice to be integrated, is that docs recommend setting up a user account for nut, one for the monitor so clients can access and another for the shutdown so one of the watchers doesn't change the shutdown script & nut provides a file that indicates when the ups should shutdown, so having that be the same on all xcp-ng systems rather than custom solution would be good.

Hannes_5253

@lknite Glad I could help and I agree.

olivierlambert

Hi,

Sadly, this use case is more meant for "non server-grade", where your machine isn't hosted in a datacenter (which is the default XCP-ng target/market).

However, I'm not against helping people doing the configuration or having an official guide to document it (I mean, in our doc)

Keep in mind we are always trying to find a balance between maintaining something (meaning time+money over other features) vs where the money is coming from (companies paying for support). If we pre-install all of this, it means we'll need to maintain it, while we still have a huge backlog of critical feature for our main (paying) target I hope you understand. Also, if we succeed and continue to grow that way with a far larger team than today, we could probably use that extra money from companies to improve integrations for the rest. But before doing it, we need to focus.

2b2bff

@olivierlambert I wonder how datacenters are doing this then in case of power loss? Or isn't that something of their concern?

olivierlambert

In a DC, you have usually 2x power feed per rack (one on the left, one on the right). So even if one power line/feed is down, it's not a problem, since all your machines are usually dual PSU.

Also, everything is backed by UPS (both feeds) inside the building, and then diesel generators are taking the load after 10/15 minutes (diesel takes few minutes to start).

So in a colo, you will never have to get your own UPS.

2b2bff

@olivierlambert in simple words: they just don't shut down. And if they would have to there are bigger problems to solve.
Thanks for answering...

gskger

@2b2bff I think that there are still some business scenarios, where this functionality would come in handy.

For example, we are running server rooms at our main production sites worldwide (no data centers, no colo, all on-site). Each features a three VMware hosts cluster with shared storage, backup, switches, and firewalls in an air-conditioned server room with adequate fire prevention/protection. All have two power feeds (A and B or left and right as Olivier called them) and all systems have dual PSUs, but the sites usually have only one power supplier and no generators.

Feed A goes to an UPS and feed B directly to the power line. If the power goes down, the UPS automatically triggers the vCenter, storage and backup to shut down when the UPS remaining runtime is below a certain threshold.

But I can perfectly understand Oliviers reasoning and there are workarounds. It all depends on your risk appetite (if that is a word in English).

2b2bff

@gskger yeah same on my place. I play around with xcp-ng at home, where this is not important, and there is no UPS. So it is not important here.
But I have built two hosts at work in a server room as well. Together with TrueNAS and a couple of other things. The APC UPS has a management card, so it can be reached via network, but somehow the hosts have to shut down gracefully if needed. That's how I stumpled upon this thread in the first place.

olivierlambert

I'm not saying it's not important in general (it depends on the use cases) But in our priorities (the "regular" DC world), it is not. For the "Edge computing" case, it might be more important, but the word "focus" doesn't have any meaning if we do everything at the same time.

And as usual, contributions are always welcome!

odeawan

Would just having the nut client be sufficient enough on the base XCP-NG to tigger a shutdown via NUT? Maintaining the NUT server seems to be a hold up and add extra complexity for XCP-NG. We all may have different DC power situations, but we could all use tools in our belt at home or the data center.

Hannes_5253

@odeawan Sure but you need a nut server. When you use the XCP-NG Server as a client you have to install the nut server on a different system. You can't install the nut server on a vm on the same host because the nut server must be installed on a system to shut down last.
So running this scenario is the most redundant and efficient way.

odeawan

Well I still don't think it is out of scope then for just the NUT client for enterprises or HomeLabs on XCP-NG.

SBCs are everywhere these days. Using a Raspberry Pi as the NUT Server in a homelab or a flavor of a more robust server for NUT seems like a solid choice. No USB passthrough to worry about, uptime on a 1500VA+ UPS, forget about it! There are a handful of guides how to get it running for a Pi or anything else (including this post).

As I think this though, I would still feel ok with another external device watching, waiting, and notifying me on a successful power off of any number of my hosts and VMs. Not all enterprises or homelabs can afford (even if their appetites want it) to get enterprise level power automations. We have our power. Break the chain. @olivierlambert

olivierlambert

Which chain? The development is open, if you want something, do it If you want to be the maintainer so we can have it updated, packaged and put in our repo (even if not bundled by default), go ahead! If we think there's people behind it, we are not against, since it's an extra package.

dj423

This post is deleted!

nomad

After NUT's grand reconfiguration there are a few things that you need to be aware of:

In order to run NUT as a monitor to shut down your XCP-ng hypervisors it is no longer sufficient to just install nut-client and enable nut-monitor.

You also need to install nut and enable nut.target or nut-monitor won't autostart. There won't be anything in journalctl either, since it isn't even trying to start - the thing that tells it to do so is the nut.target and if that's missing nothing will ever trigger.

yum install nut nut-client --enablerepo=epel

make your edits in nut.conf and upsmon.conf then

systemctl enable nut.target 
systemctl enable nut-monitor 
systemctl start nut-monitor

CodeMercenary

@nomad What do you mean by the grand reconfiguration? Is there a new version that changes how things work?