In the past few weeks I have seen a couple customers using Direct IO when running 10.1C on Windows Servers. What is curious is that it was not set for all of the production databases on the same server.
Other than someone tinkering I see no basis for implementing this.
Am I missing something obvious? I don't think so but figured I'd look for confirmation.
These customers both are struggling with performance issues even under a light load.
Thanks, Bob
Remove it. It is unlikely doing any good.
On Tuesday in my presentation on DB startup parameters I said that there was no more need for -directio. Dan Foreman corrected me: he found a particular case under Solaris with a less-than-optimal disk I/O subsystem where -directio was helpful.
If you could describe the issues we can try to help. Turning on PerfMon recording for 24h is also a good idea. You may see something that stands out during the perf issues. I had a similar issue a couple of months ago and it turned out to be Windows losing its mind (again). SYS CPU% would jump up to 50-60% for no reason for extended periods.
In the ancient days you could use -directio to overcome some UNIX filesystem issues with varying levels of success. These days it should just be removed whenever you see it assuming you are not running V8/V9 on ancient versions of UNIX/AIX.
If they are having performance issues it isn't related to -directio. I would start with examining the hardware (CPUs and Memory) and then start looking into the DB (promon/protop) and network.
Thanks Paul. I was sitting right next to Dan in your session while he was writing his slide deck for the next talk :-)
I have never seen Direct IO used on Windows. I am pretty sure that these customers have never had any experienced help look at things before. I would guess this is more a matter of "let's see what this does."
So far, no one left at either company has any idea why these got set. I intend on removing it and seeing if we see any adverse reactions. Just odd to see exact same setup randomly at a couple accounts in such a short period of time.