title: CLOB storage Oracle 11g
body: <p>I have a encountered very strange behavior of Oracle <code>LOB</code>. 
  Situation: We have partitioned IOT that contains <code>CLOB</code> column. <code>CLOB</code> has separate <code>LOB</code> storage set up with <code>LOGGING RETENTION</code> and <code>DISABLE IN ROW STORAGE</code> options. <code>CHUNK</code> size is 8192bytes. <code>PCTFREE</code> is set default(null in <code>dba_tables</code>). 
  Now, we need to create a test case with certain amount of <code>CLOB</code>s loaded. we have chosen 19.5KB <code>CLOB</code>. After loading this <code>CLOB</code> 40 million times(used for perf. testing, does not matter about content) - the size on file system and in <code>dba_data_files</code> is 1230GB. </p>
  
  <p>Question:</p>
  
  <p>We estimated size of 40mil. <code>CLOB</code>s with size 19.5KB to ~780GB. How did we get 450GB more? I would guess it has something to do with <code>CHUNK</code> size - 19.5KB would use 3 <code>CHUNK</code>s, thus being size 24KB, which is still only 960GB. <code>LOB</code> index is around 2GBs. 
  Does anybody have an idea?(sorry for poor explanation)(P.S. running ORACLE 11g)</p>
  
  <p>Thank you in advance!</p>