I have found that I/O requests that involve the same spindles more than onec in a single request simply do not perform. It is generally better to hit the LUN more times for I/Os sized rightly to not wrap an entire stripe set. So, if I have 2 disks and intend to scan them with 1MB reads, uh, I don't set the stripe width to 32KB. Having the array line up 16 chucks on each disk to satisfy a single transfer request is just a mess. In fact, I generally set stripe width to a value larger than 1MB if the kit supports it. YMMV ... this is a religious topic you know... :-) ________________________________ From: Vlad Sadilovskiy [mailto:vlovsky@xxxxxxxxx] Sent: Monday, December 11, 2006 1:29 PM To: kevinc@xxxxxxxxxxxxx Cc: oracle-l Subject: Re: I/O and db_file_multiblock_read_count How does number of disk hits for larger I/O corresponds to number of hits for smaller I/O in respect to the whole process. It should not be more should it? Unless same data gets read twice.