See my answers inline below. Thanks again for all the help! On Nov 16, 2007 2:47 AM, Greg Rahn <greg@xxxxxxxxxxxxxxxxxx> wrote: > What are the disk stats during the backups (from iostat)? Some things > I would investigate: > - are the target drives saturated? > - are the I/O channels saturated? I presume these things can only be known during backup times. Any special parameters to pass to iostat to get the specific information for these questions? Should I take a sample every hour during the level 0? > - do /rman and the db file luns share physical spindles? (hopefully not) Right now they do actually. It is a temporary situation until we can move some more disk around in Jan/Feb 2008. Perhaps any real investigation is moot until we get it isolated? To Brandon: /rman is RAID 10. > I would suggest that you should have N luns where N is the number of > parallel streams. This allows N I/O SCSI queues to be simultaneously > serviced vs. one. Think of this like more check out lanes at the > grocery store. So this would be something like /rman1, /rman2, /rman3, /rman4 when I have parallelism=4? I presume I need to configure the individual channels then to each write to one of those locations. Perhaps I'm confusing terms. > Compression has the CPU overhead, but reduces the IO bandwidth and > storage space requirement. If you are not I/O bound (or space) then > it won't provide any visible performance gains - it will just consume > more CPU. It's basically a trade off. Just to confirm, last night's level 1 backup saw a load as high as 22.43. I'll try to get I/O readings this weekend. > Ultimately you want the target writes to be the bottleneck, but > operating at optimal efficiency. I assumed as much, I just want to make sure that the bottleneck is as wide as can be. ;) To Alex G: I'll try to get 10046 traces as well this weekend. -- Don Seiler http://seilerwerks.wordpress.com ultimate: http://www.mufc.us -- //www.freelists.org/webpage/oracle-l