That's a very small sample though - do you see that behaviour consistently? Maybe the blocks were cached by the OS or SAN when you ran with dbfmbrc=16, but they actually had to be read from physical disk when you ran with dbfmbrc=128? -----Original Message----- From: Kevin Lidh [mailto:kevin.lidh@xxxxxxxxx] Oracle requested more blocks in the single read (126) and got them. It just took longer than 8 requests for less blocks (16) per read. Privileged/Confidential Information may be contained in this message or attachments hereto. Please advise immediately if you or your employer do not consent to Internet email for messages of this kind. Opinions, conclusions and other information in this message that do not relate to the official business of this company shall be understood as neither given nor endorsed by it. -- //www.freelists.org/webpage/oracle-l