For the past several weeks, the Archive has been experiencing brief, but somewhat frequent, periods of downtime due to our search engine becoming overwhelmed. This is because we're working on upgrading from Elasticsearch 0.90 to 6.0, so only half of the servers we'd typically use to power the Archive's search engine are available -- the others are running the upgraded version so we can test it.
The good news is the downtime should stop once our upgrade is complete and all servers are running Elasticsearch 6.0. While we can't estimate when that will be, we're working hard to wrap up our testing and fix any remaining bugs as quickly as possible, and we'll have more information on the upgrade coming soon.
We've made some minor adjustments to minimize the downtime, although you may notice some slowness, and downtime may still occur during particularly busy periods. Please rest assured we have systems in place to alert our volunteers of the issue, and it will generally be resolved within 30 minutes.
For now, we offer our sincerest apologies, and we'll continue to monitor the situation and make whatever adjustments we can to improve it. As always, you can follow @AO3_Status on Twitter for updates.