We have received numerous reports from users about the closure of the c/android community. While we fully support the original community owners’ decision to move to another instance, it will eventually be necessary to open up the community on Lemmy.world. The beauty of the fediverse is that multiple communities on the same subject can exist in different instances. However, if you can no longer moderate a community on Lemmy for any reason, it is important to pass it on to individuals who are willing and able to do so.
To ensure the best interests of our instance members, it is necessary to establish boundaries. Holding onto a community name cannot be a permanent arrangement. It’s important to consider our users’ ongoing interest in the community if they wish it to continue. While we acknowledge the objective of consolidating communities, current community members ultimately decide whether they wish to join the new community at lemdro.id.
To ensure a smooth transition, we will keep the community locked for another week, providing ample time to inform the active user base about the move to the new instance at https://lemmy.world/c/[email protected].
User U1 couldn’t access anything, since their account is at hostone and hostone is down. But they could log in with a different account on a different instance (or just lurk without logging in) and be fine.
User U2 would be almost entirely unaffected, since User U2 is on hosttwo, which is unaffected. B@hosttwo would be entirely untouched, and User U2 would even still be able to access A@hostone. Sort of.
All along, when User U2 accessed A@hostone, they were never actually accessing A@hostone directly - they were actually accessing a mirror that’s hosted on hosttwo - A@hostone@hosttwo. So the only effect of hostone bring down is that A@hostone@hosttwo wouldn’t get any new content from A@hostone (or from any of the other federated mirrors - A@hostone@hostthree or A@hostone@hostfour and so on). But all of the content that was already at A@hostone@hosttwo would still be there and could (presumably) still be accessed. New content could (presumably) even be added there, but since it wouldn’t be able to sync back up with hostone, it wouldn’t show up anywhere else - it would just be at A@hostone@hosttwo.
And a note on those (presumably)s - internally, the lemmy/kbin/whatever software would recognize that it was failing in its attempts to sync with hostone, and likely that it was failing to even contact hostone. I don’t know how the assorted pieces of software - kbin or lemmy or mastodon or whatever - handle that. If they ignored it and just kept trying to sync with hostone and failing, then User U2 might not ever even be aware of the fact that hostone is down, since even A@hostone@hosttwo would look the same - it just wouldn’t be syncing with hostone, so wouldn’t be getting any new content from there or from any of the other federated versions of A@hostone, and User U2 might eventually notice that.
It’s also possible though that the software could be set up to tell User U2 that hostone was offline, and it might even be set up so that it would refuse to accept new content at A@hostone@hosttwo until it could get back to syncing content with hostone. I don’t know why it would be done that way, but it could.
That’s brilliant, thanks for the in-depth answer.