title: how can change derby to READ/WRITE mode
body: <p>I have a Derby database that is giving me a read-only error. The database was working fine, up until last week when disk ran out of space:</p>
  
  <pre><code>Caused by: java.io.IOException: No space left on device
          at java.io.RandomAccessFile.writeBytes0(Native Method)
          at java.io.RandomAccessFile.writeBytes(RandomAccessFile.java:520)
          at java.io.RandomAccessFile.write(RandomAccessFile.java:550)
          at org.apache.derby.impl.store.raw.log.LogAccessFile.writeToLog(Unknown Source)
          at org.apache.derby.impl.store.raw.log.LogAccessFile.flushDirtyBuffers(Unknown Source)
          ... 23 more
  </code></pre>
  
  <p>I cleaned up disk and there are 80% of disk is freed for derby. But the derby is still in read-only mode:</p>
  
  <pre><code>java.sql.SQLException: An SQL data change is not permitted for a read-only connection, user or database.
  org.apache.derby.impl.jdbc.EmbedSQLException: An SQL data change is not permitted for a read-only connection, user or database.
  org.apache.derby.iapi.error.StandardException: An SQL data change is not permitted for a read-only connection, user or database.
  </code></pre>
  
  <p>I found there is a db.lck file (which file size is 0) there, can I remove that file?  Is there any other way to change it read/write mode?
  Thank you!</p>