Database maintenance Error 503

The database is offline for a short maintenance, please retry in a moment.

QUERY: SELECT views, id, thread_title, posts, poster_user_id, poster_username, posted_time, sticky, locked, moved_from_section_id, moved_time, last_post_time, del, del_text, last_post_username, last_post_userid, last_post_id, section_id, type, poll_id, files_attached FROM forum_threads WHERE section_id = 27856 AND del != 1 AND del != 5 ORDER BY sticky DESC, last_post_time DESC LIMIT 0, 100<br> ERROR: Error writing file '/tmp/MYbG417N' (Errcode: 28)<br>