title: Error 21 when trying to delete a SQL Server DB
body: <p>I had a SQL Server database on an external HDD. I forgot to detach the DB. I do not need it anymore, but I am unable to delete or take it off line.</p>
  <p>When I try to delete or take the DB offline, I get the following error.</p>
  <blockquote>
  <p>Msg 823, Level 24, State 2, Line 7</p>
  <p>The operating system returned
  error 21(The device is not ready.) to SQL Server during a read at
  offset 0x00000000012000 in file 'E:\Kenya Air\Monet - Paulus.mdf'.
  Additional messages in the SQL Server error log and system event log
  may provide more detail. This is a severe system-level error condition
  that threatens database integrity and must be corrected immediately.
  Complete a full database consistency check (DBCC CHECKDB). This error
  can be caused by many factors; for more information, see SQL Server
  Books Online.</p>
  </blockquote>
  <p>I have tried to run a DBCC CHECK, but I get the same error.</p>