Also note that the "log file parallel write" is not really random IO, compared to a "db file parallel write" which may write hundred(s) of buffers into random locations in a single vector IO call. That makes a difference even on non-exadata without IORM too (especially if there's no write-cache for DBWR writes or the storage array cache destaging can't keep up with the write workload). -- Tanel Poder New Online Training! http://blog.tanelpoder.com/seminar On Fri, Jan 4, 2013 at 12:31 AM, John Clarke <john.clarke@xxxxxxxxxxxx>wrote: > The behavior I was describing was specific to IORM & Exadata I/Os. To my > knowledge there isn't a direct parallel to this for ASM in general, but I'm > open to be educated ... > With ASM without Exadata, background I/O is queued according to your async > I/O configuration (or synchronously depending on O/S and init.ora > settings), but the operating system or Oracle wouldn't interject any > prioritization algorithm for LGWR I/Os vs DBWR I/Os. > -- //www.freelists.org/webpage/oracle-l