this post was submitted on 11 Jun 2023
189 points (98.5% liked)
Asklemmy
43760 readers
1079 users here now
A loosely moderated place to ask open-ended questions
If your post meets the following criteria, it's welcome here!
- Open-ended question
- Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
- Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
- Not ad nauseam inducing: please make sure it is a question that would be new to most members
- An actual topic of discussion
Looking for support?
Looking for a community?
- Lemmyverse: community search
- sub.rehab: maps old subreddits to fediverse options, marks official as such
- [email protected]: a community for finding communities
~Icon~ ~by~ ~@Double_[email protected]~
founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
What does ‘horizontally scalable’ mean here? I haven’t come across that before.
This is what I think, but if anyone understands it differently please correct me.
Vertical scalability refers to scaling within a single instance. More users join and they post more content, increasing the amount of disk space needed to hold that memory, network bandwidth to handle many users downloading comments and images at once, and processing power.
Horizontal scaling refers to the lemmyverse growing because of the addition of new instances. The problem in this form of scaling is due to the resources that an instance has to use due to its interactions with other instances. So, you may create a small instance without a lot of users, but the instance might still need a lot of resources if it attempts to retrieve a lot of information (posts, comments, user information, etc) from the other larger instances. For example, at some point a community in lemmy.ml might be so popular that subscribing to that community from a small instance would be too much of a burden on the smaller instance because of the amount of memory required to save the constant stream of new posts. The horizontal scaling is a problem when the lemmyverse becomes so large that a machine with only a small amount of resources is no longer able to be part of the lemmyverse because its memory gets filled up in a few hours or days.
I don't believe this is how it works though.
Let's say your tiny 3 person instance is connected to a big one. I believe it only pulls in content from the communities somebody from the small instance is subscribed too. Correct me if I'm wrong.
That's what they're saying.
Essentially - if someone from the small instance subscribes to a community that has a ton of data (huge post volume, images, whatever), the small instance needs to pull data over from the larger instance. At some point there may be communities that are so large small instances can't pull them in without tanking.
I wonder if there is a way to get around this? maybe smaller instances will have to be text-only?
Could that be solved by caching? Can't the smaller instance avoid some duplication?
If I'm reading the protocol right, it's probably larger instances that will avoid more duplication, since:
I'm not sure I see where you see caching fitting in.
I am surprised I don't see some kind of lower resolution digest concept in the protocol (which might be what you're looking for)
maybe I phrased that poorly and you didn't understand what I was trying to say. The size of the bigger instance shouldn't matter at all because only data from communities is pulled, that a member of the smaller instance is subscribed to. So if the bigger instance has 1000 members or 2 million members wouldn't make a difference. The only thing relevant should be how active the communities are that members are subscribed to.
Sure, the sizes of the communities is what matters (multiplied by the number of communities users on the server care about).
I think most of us are assuming larger instances are more likely to host the larger communities.
Actually, if I'm reading the protocol right, it'd be hard for a small server to host a highly active community anyway (for some value of highly active). So yes, some 2 person instance that was created to offload stuff could be the primary host for a massive community, but in practice it won't.
We are arguing about very specific things here anyway. And I generally do share your concerns about how well this is going to scale. I want this to do well.
Agreed 100%