Re: Performance question: single datafile vs multiple datafiles

Sybrand Bakker wrote:
>
> On Fri, 01 Mar 2002 18:28:10 GMT, Ricky Sanchez <rsanchez_at_more.net>
> wrote:
>
> >Sybrand-
> >
> >How does file size relate to dbwr average scan depth?
> >
> >Also, in a non-raid environment, don't multiple data files afford the
> >opportunity to spread IO among many disks and reduce latency?
> >
> >- ricky
> >
>
> <quote>
> there is no reason to have multiple
> datafiles for a single tablespace on the *same physical disk*.
> </quote, asterixes added>
>
> Also I didn't discuss file size, I discussed the *number* of files.
> I consistently get complaints from Toad on dbwr_average_scan_depth,
> telling me the number of files is too high, even if there is not much
> difference between db_files and the actual number of files.
> This might be a V7 thingy, but Toad is complaining about it.
> Usually the complaint arises for databases with say 7-10 tablespaces
> each consisting of 5 or more files, all files of a single tablespace
> being located on the same disk. Does this reduce latency?
> I don't think so. I also think in your scenario you should software
> stripe your tables. If you don't do that, it is unlikely to help you.
>
> So now please tell me I'm an idiot. You have done that before to me,
> so I'm prepared for it.
>
> Regards
>
> Sybrand Bakker, Senior Oracle DBA
>
> To reply remove -verwijderdit from my e-mail address

I think Toad is wrong ie out of date. dbwr settings used to be dependent on the db_files parameter. From 8i, I'm pretty sure it is constant (the value of which being dependent on the platform).

hth
connor

-- 
==============================
Connor McDonald

http://www.oracledba.co.uk

"Some days you're the pigeon, some days you're the statue..."