Re: Very high 'log file sync' wait time with no 'log file parallel write' wait time

EscVector wrote:
> mccmx_at_hotmail.com wrote:
> > > Are your logs on different mounts? Are you on RAID-5. Is it Direct
> > > Path, looks like not.
> > > I hope you don't have your windows page file on the same volume as the
> > > redo.
> >
> > What makes you so sure it is an I/O problem - I've already said that we
> > are seeing no waits for 'log file parallel write', which suggest that
> > log file I/O is not the problem..
> >
> > Matt
> "Me! I not sure of anything..." It's is simply the first place I
> start even when looking at a trace file. Without knowing this info, I
> can't be sure the issue isn't simpler than it seems. I'm not sure why
> you are saying that I/O is not the problem w/o log file parallel write.
> Better I/O could improve the sync performance. Large frequent commits
> and a too large log buffer can also be a cause.

I take it back, I do see why.. I'm sometimes over zealous in my rant against RAID-5.
The question I should have asked is why not just increase UNDO. What's the issue with that? UNDO is cheap compared to trying to debug why a commit is happening when one should not during a imp with large buffer and commit=y... Question, does the wait happen if the commit=y is removed. If not, nuff said... Up Undo, get it done. For educational purposes, then fine, keep it going, probably a bug, open a tar. Received on Fri Dec 01 2006 - 21:43:06 CST