InnoDB gone missing as database type - has anyone seen this error before? I'm working on the Drupal 7 site that's currently on Dreamhost.

Since this morning, the site is showing the following error message:


  Error
  The website encountered an unexpected error. Please try again
  later.
  Error message PDOException: SQLSTATE[42000]: Syntax error or
  access violation: 1286 Unknown table engine 'InnoDB': SELECT expire,
  value FROM {semaphore} WHERE name = :name; Array ( [:name] =>
  variable_init ) in lock_may_be_available() (line 167 of
  /home/mysite.com/includes/lock.inc). Uncaught exception thrown in
  shutdown function.
  
  PDOException: SQLSTATE[42000]: Syntax error or access violation: 1286
  Unknown table engine &#039;InnoDB&#039;: DELETE FROM {semaphore} WHERE
  (value = :db_condition_placeholder_0) ; Array (
  [:db_condition_placeholder_0] =&gt; 7584349655055df9b66b5c9.36234254 )
  in lock_release_all() (line 269 of
  /home/mysite.com/includes/lock.inc).


Has anyone seen this sort of error before? Yesterday, my database showed as InnoDB in PHPMyAdmin; today there's nothing showing as "type."
On Debian 6, this can also happen when you change the innodb_log_file_size parameter. Sometimes mysql does not start; other times, it just starts up, but the InnoDB engine is not enabled. The solution is to remove ib_logfiles from /var/lib/mysql and restart mysql.

See this issue in drupal.org.