Not just speaking technically but economically. As user number mount up their post is just going to add up. I know instaces may distribute user, but server space isn’t going to go down for anyone. It just seems like built to fall.
Economically, I’d say yes. You can get a vServer for like 10€ per month and it’ll have something like 200GB of storage and more than enough computing power to run lemmy. Text is small so only posting many pictures/videos could be a problem. But 10€/$ is kinda affordable even for a single person and the storage should last you quite a bit. Even if you share the instance with a few of your friends.
And you could even have a community or non-profit pay for a larger vServer and ask everyone to contribute a bit of money. I’d be surprised if you needed more than say $3 per month and person. (probably less?)
So economically, I’d say it’s easily doable.
Technically, depends on what the developers do. There are still quite some issues to fix. And I’d consider caching and how easy it is to set up an instance for your community more technical problems.
Lemmy is setup quite ok to scale users and traffic, since the users are (theoretically) distributed over many instances. In reality it doesn’t work out perfectly, since people generally are more likely to join the biggest instances, so there’s quite an imbalance there.
But what’s worse is content replication. As soon as an user requests to look at a community for the first time, the whole community will get completely replicated on that user’s instance. So any decently sized instance will pretty much replicate almost all communities, at least all that have content.
There is no scaling or storage balancing mechanic here. Even if no user ever touches that replicated community again, it will continue to be replicated, will fetch all new posts/comments and store them in the instance.
There is also currently no workaround to this (like there is for users/traffic, which you can just tell to join a different instance).
So if Lemmy ever gets to the point where gigabytes of data gets posted every day (which is only about 1000 pictures a day) storage demand will get so high, that hosting an instance will be seriously costly, which will probably lead to instances without any kind of cash flow shutting down, which will in turn lead to more users and thus traffic on the remaining instances.
I guess, that’s one of the biggest technical (and conceptual) roadblocks that need to be addressed if Lemmy ever grows that big.
As the project evolves, there will be fixes for that kind of problem, it is not an immediate problem.
Is there a feature to migrate users from one instance to another ?
I think it will be important when some instances will shut down. As long as people can move, then I think we can spread out the load.
I know my instance is handling the load very well and I’m really grateful for it.
There is a program I used to transfer my subscriptions and settings to a different instance.
Anything is possible with enough work and proper planning.
Hope so. I’m definitely telling people about it.