Re: Redo logs a Quick I/O enabled file system

On Sep 13, 3:38 pm, "fitzjarr..._at_cox.net" <fitzjarr..._at_cox.net> wrote:
> On Sep 13, 1:35 pm, Mike <n00s..._at_comcast.net> wrote:
>
> > What is the impact of placing the Oracle redo logs on a Veritas Quick
> > I/O enabled file system?
>
> > --Thanks,
> > --Mike Jr.
>
> No 'impact', really, but no benefit, either, as they are written
> serially. I found no reason to place redo logs on such a file system.

David,
 Thank you. I should have been more specific and said "Cached Quick I/ O". I know that for a UFS file system Direct I/O should be specified for the redo logs to maximize performance. UFS caching can kill performance.

I am looking at a system where the redo logs have been placed on a VxFS with "Cached Quick I/O" enabled. Will this impact performance the same way that cached UFS would? Or is Veritas smarter than this? I am seeing I/O contention (vmstat showing at least one process blocked and CPU > 80% idle; iostat shows the device containing the redo logs at > 60% busy). I was wondering if moving the redo logs to a UFS Direct I/O file system would improve things.

Thanks again,
Mike Jr.
>
> David Fitzjarrell
Received on Thu Sep 13 2007 - 15:04:05 CDT