Re: Extent Allocation among Multiple Datafiles ?

"EnderW" <ender29_at_my-deja.com> wrote in message news:8p9l20$bha$1_at_nnrp1.deja.com...
> 1) Then if I have three different file systems to lay my tablespaces
> on. Isn't it better to create three different datafiles on each file
> system for each tablespace ? That way, the extents will be grabbed in a
> round robin fashion and will create an effect similiar to striping. I
> can set my extents to be 64K and set pctincrease to 0.
> 2) Other case, laying one tablespace on one filesystem. And the other
> tablespace on another filesystem. And the third one on another file
> system and back to the first one.
>
> I would rather go with the first case. Though I am thinking of applying
> every tablespace out there in this manner (rollback, system and even
> redo logs). Any suggestions ?

i suggest you think about the impact of spreading every one of your tablespaces across every disk is going to have...

1. on your backup and recovery strategy. for example, if you lose drive1, which files, logs, and tablespaces will be impacted. what if you lose drive2 ?
2. on i/o performance. redo logs can exhibit i/o characteristics significantly different from other datafiles...
3. on the addition of more hard disks. that is, will you want or need to redistribute log files and datafiles when you add more disks ?

just a few things to think about.

>
> In article <968314038.14856.0.nnrp-03.9e984b29_at_news.demon.co.uk>,
> "Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> wrote:
> >
> > I can't remember which version of Oracle (possibly very late 7)
> > it appeared in, but with multiple files in a tablespace Oracle uses a
> > round-robin method for allocating extents on a per-segment.
> >
> > i.e. if you create two tables, their first extents will both be in
> > 'file 1', their second in 'file 2' and so on.
> >
> > --
> >
> > Jonathan Lewis
> > Yet another Oracle-related web site: http://www.jlcomp.demon.co.uk
> >
> > EnderW wrote in message <8p7207$9rf$1_at_nnrp1.deja.com>...
> > > Hi,
> > > I was reading a book on DB2 ( no flames :) . Anyhow while reading a
> > >book, I wondered if I have a tablespace that has 3 data files on 3
> > >diff. filesystems. Does Oracle have a switching mechanism among those
> > >datafiles ? Suppose I grab one extent and use it and the next extent
 I
> > >grab it from the second datafile and the third extent from the third
> > >datafile ? Or grab until we exhaust all the space on the datafile
 then
> > >move on to the second one ? Thanks.
> > >
> > >PS. If I am missing something, please excuse me since I am close to
> > >12AM..
> > >
> > >--
> > >Ender Wiggin
> > >
> > >
> > >Sent via Deja.com http://www.deja.com/
> > >Before you buy.
> >
> >
>
> --
> Ender Wiggin
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>
Received on Fri Sep 08 2000 - 01:03:21 CDT