title: SQL Server log file fills under Simple recovery model
body: <p>I have a database in SQL Server 2008 R2 that has millions of files stored in it as varbinary blobs.  I set up a process last week to do the following:</p>
  
  <ol>
  <li>Use some Entity Framework code to get the row (i.e. entity) that has the blob.</li>
  <li>Copy the blob stream to an object store.</li>
  <li>Update entity in the database with the new Object ID from the store.</li>
  </ol>
  
  <p>I have 30 threads doing this constantly and the process will still take several days.  A couple days ago the database log file filled up and I'm sure it had to be caused by this process.  I decided point-in-time backups are not critical for this database and set the database to use the Simple recovery model.  Then yesterday I got errors from my process again that said the log file filled up!  How is this possible in simple mode?!  Any idea what I can do to stop this from happening?  When I monitor the log file SQL Server lets it get to 7% full and then truncates it down to zero so I'm super confused.  It seems as though the log file starts to grow unchecked when the full backup begins...</p>