Comment by Puts
1 month ago
My experience after 20 years in the hosting industry is that customers in general have more downtime due to self-inflicted over-engineered replication, or split brain errors than actual hardware failures. One server is the simplest and most reliable setup, and if you have backup and automated provisioning you can just re-deploy your entire environment in less than the time it takes to debug a complex multi-server setup.
I'm not saying everybody should do this. There are of-course a lot of services that can't afford even a minute of downtime. But there is also a lot of companies that would benefit from a simpler setup.
Yep. I know people will say, “it’s just a homelab,” but hear me out: I’ve ran positively ancient Dell R620s in a Proxmox cluster for years. At least five. Other than moving them from TX to NC, the cluster has had 100% uptime. When I’ve needed to do maintenance, I drop one at a time, and it maintains quorum, as expected. I’ll reiterate that this is on circa-2012 hardware.
In all those years, I’ve had precisely one actual hardware failure: a PSU went out. They’re redundant, so nothing happened, and I replaced it.
Servers are remarkably resilient.
EDIT: 100% uptime modulo power failure. I have a rack UPS, and a generator, but once I discovered the hard way that the UPS batteries couldn’t hold a charge long enough to keep the rack up while I brought the generator online.
Being as I love minor disaster anecdotes where doing all the "right things" seem to not make any difference :).
We had a rack in data center, and we wanted to put local UPS on critical machines in the rack.
But the data center went on and on about their awesome power grid (shared with a fire station, so no administrative power loss), on site generators, etc., and wouldn't let us.
Sure enough, one day the entire rack went dark.
It was the power strip on the data centers rack that failed. All the backups grids in the world can't get through a dead power strip.
(FYI, family member lost their home due to a power strip, so, again, anecdotally, if you have any older power strips (5-7+ years) sitting under your desk at home, you may want to consider swapping it out for a new one.)
For sure, things can and will go wrong. For critical services, I’d want to split them up into separate racks for precisely that reason.
Re: power strips, thanks for the reminder. I’m usually diligent about that, but forgot about one my wife uses. Replacement coming today.
My single on-premise Exchange server is drastically more reliable than Microsoft's massive globally resilient whatever Exchange Online, and it costs me a couple hours of work on occasion. I probably have half their downtime, and most of mine is scheduled when nobody needs the server anyhow.
I'm not a better engineer, I just have drastically fewer failure modes.
Do you develop and manage the server alone? It's a quite a different reality when you have a big team.
Mostly myself but I am able to grab a few additional resources when needed. (Server migration is still, in fact, not fun!)
A lot of this attitude comes from the bad old days of 90s and early 2000s spinning disk. Those things failed a lot. It made everyone think you are going to have constant outages if you don’t cluster everything.
Today’s systems don’t fail nearly as often if you use high quality stuff and don’t beat the absolute hell out of SSD. Another trick is to overprovision SSD to allow wear leveling to work better and reduce overall write load.
Do that and a typical box will run years and years with no issues.
> My experience after 20 years in the hosting industry is that customers in general have more downtime due to self-inflicted over-engineered replication, or split brain errors than actual hardware failures.
I think you misread OP. "Single point of failure" doesn't mean the only failure modes are hardware failures. It means that if something happens to your nodes whether it's hardware failure or power outage or someone stumbling on your power/network cable, or even having a single service crashing, this means you have a major outage on your hands.
These types of outages are trivially avoided with a basic understanding of well-architected frameworks, which explicitly address the risk represented by single points of failure.
don't you think it's highly unlikely that someone will stumble over the power cable in a hosted datacenter like hetzner? and even if, you could just run a provisioned secondary server that jumps in if the first becomes unavailable and still be much cheaper.
> don't you think it's highly unlikely that someone will stumble over the power cable in a hosted datacenter like hetzner?
You're not getting the point. The point is that if you use a single node to host your whole web app, you are creating a system where many failure modes, which otherwise could not even be an issue, can easily trigger high-severity outages.
> and even if, you could just run a provisioned secondary server (...)
Congratulations, you are no longer using "one big server", thus defeating the whole purpose behind this approach and learning the lesson that everyone doing cloud engineering work is already well aware.
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I don't know about Hetzner, but the failure case isn't usually tripping over power plugs. It's putting a longer server in the rack above/below yours and pushing the power plug out of the back of your server.
Either way, stuff happens, figuring out what your actual requirements around uptime, time to response, and time to resolution is important before you build a nine nines solution when eight eights is sufficient. :p
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It's unlikely, but it happens. In the mid 2000's I had some servers at a colo. They were doing electrical work and took out power to a bunch of racks, including ours. Those environments are not static.
In my experience, my personal services have gone down exactly zero times. Actually not entirely true, but every time they stopped working the servers had simply run out of disk space.
The number of production incidents on our corporate mishmash of lambda, ecs, rds, fargate, ec2, eks etc? It’s a good week when something doesn’t go wrong. Somehow the logging setup is better on the personal stuff too.
I also have seem the opposite somewhat frenquently: some team screws up the server and unrelated stable services that are running since forever (on the same server) are now affected due messing up the environment.
Not to mention the other leading cause of outages: UPS's.
Sigh.
UPSes always seem to have strange failure modes. I've had a couple fail after a power failure. The batteries died and they wouldn't come back up automatically when the power came back. They didn't warn me about the dead battery until after...
That’s why they have self-tests. Learned that one the hard way myself.
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