Strangely enough, it was that same article which prompted my test on my HP-UX 11.11 system with the same results as you (and the same question on the list about a week ago). I would see it taking almost three times as long to retrieve the same 128k of data in one I/O request with the dfmrc set to 128 than when it was set to 16 with 8 I/O requests. I looked at Metalink, and found a reference to maxio (assuming vol_maxio on my system) and found that it's set to 256. The implication is that the max I/O for my system is 256k so if my block size is 8k, the biggest dfmrc I should have would be 32 (I'm testing this as I type). My assumption is that if I set it higher, there is an attempt to make the multiple I/O requests and assemble them into a single I/O response and the overhead is the additional time. But that's speculation on my part until I have concrete numbers. On Tue, 2006-12-19 at 13:52 -0600, Don Seiler wrote: > For reference, this was the guide I was following: > http://www.dizwell.com/prod/node/436 . HJR makes a case for not > having to flush the buffer cache. However it's possible that I > incorrectly assumed that applied to me. > > Don. > -- //www.freelists.org/webpage/oracle-l