How do you scale a mastodon server?

I'm unfamiliar with running an active Mastodon instance, so I can't speak from experience on what's needed for that level of active users. That said, I did some research and think I found some helpful information to get you started.

Reading your question regarding whether to consider a 2GB plan be enough to power your Mastodon instance, I thought of two ways to approach this:

• Resizing the compute instance to provide additional resources as needed
• Tuning an instance to get the most out of whichever plan you choose before needing to resize the compute instance

Resizing a compute instance is easy to accomplish through the Cloud Manager. Our How to Resize a Compute Instance guide covers the steps to do this. When using the Marketplace App for Mastodon, we recommend a 2GB Shared CPU Compute Instance or higher. To be clear, that's the minimum needed.

In my research, I found that sometimes poor service configurations can result in slow performance and/or a low average load. The Scaling Mastodon page on the official Mastodon documentation page covers the variables regarding load and what to consider when needing tweeks for performance. Back in 2017, the CEO and founder of Mastodon published a blog post detailing where load comes from and what settings to configure when scaling their Mastodon instance: Scaling Mastodon - Mastodon Blog. I'd start here to better understand the technical aspects of running a Mastodon instance.

Additionally, here's a GitHub post which provides some basic requirements that looks to be a useful guideline on when to scale:

• mastodon-documentation/Running-Mastodon/Resources-needed.md at master · McKael/mastodon-documentation · GitHub

More specifically to your use case, I found a thread from Mastodon subreddit where a user had 45 members registered and that their server's specification is running a 2 GB memory, 1 vCPU, 50 GB disk, and is using Ubuntu 20.04 (LTS) x64.