Recently our search server hit a magical 2GB limit on search index sizes and consequently we’ve got a corrupted track search index. We’re in the process of building a new one, but the process takes about 7.5 hours. So, we will not have track searches or taglookup functionality (for tracks) for the next 7-8 hours. I anticipate having this fixed around 22:00 PDT (6:00UTC).
I apologize for the inconvenience.
(And, sorry no, the mirror server won’t help since that relies on the main search server server too)
MetaBrainz Blog 