Since it has been the source of some confusion:
Infosec.space is running on much, much smaller hardware than Infosec.exchange. Both have ample room for substantial growth, however. I continue to identify and address bottlenecks, but things are quite stable now.
You can download your posts by clicking the “request archive” button at the bottom of the settings, import & export page.
Mastodon does not support importing posts. Setting up shop on a new instance is starting over from a posts perspective. Your followers will transfer automatically and you can refollow based on an export of your follows (not automatic). There are some GitHub issues open against mastodon to support this, but it’s not on the roadmap as far as I am aware. Firefish and iceshrimp do support important posts, but the software is much less refined than mastodon is. Infosec.town and fedia.social both run this software.