Re: Extent Allocation among Multiple Datafiles ?

I agree that it is a nightmare if one of the disks crashes. My only aim is to minimize the disk contention at this time. The product loads a million rows in to the database in a matter of hours. Then during the day, the users do the query. So when loading the rows, I have thought creating a such striping effect might be beneficial. Though I have to know each disk characteristic, how many KB's I can read/write in one request before I ran into an I/O wait. Any ideas on how I can find those values. Any unix commands I can try ? As for redo logs what are the possible effects of such a layout ? Thanks in advance.

In article <5i%t5.753$3S.147821_at_nnrp1.sbc.net>,   "spencer" <spencerp_at_swbell.net> wrote:
> "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.
> >
>
>

--
Ender Wiggin


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Before you buy.