Re: Best size for datafiles

Remembering that the data file is the smallest unit of backup (and restore until 9i), then 5Gb files sound like a dreadful idea, though with the right hardware I can imagine it working.

The balance is: the more files, the more opportunity for I/O distribution around different devices, and the more flexibility and ease you have in a backup strategy. But also, the more files, the longer checkpoints take.

Given that I take the risk of Instance failure to be low-ish, I tend to recommend huge log files that never switch, thus minimising the number of checkpoints. And given few checkpoints, I can't see what possible nightmares there can be with multiple smaller data files, instead of fewer humungous ones.

Go on: enlighten me!

Regards
HJR

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"Dusan Bolek" <pagesflames_at_usa.net> wrote in message
news:1e8276d6.0110170402.5bc36b7f_at_posting.google.com...


> willjamu_at_mindspring.com (James A. Williams) wrote in message

news:<3bcd26c9.9000852_at_news.mindspring.com>...


> > I am on a Solaris Platform running  8.1.7. I am creating a .5 tb

> > datawarehouse.

> >

> >

> > I am going to have a lot of datafiles.

> >

> > A smaller datafile spread out generally performs better.

> >

> >

> > I like 500 mb but will go with 1000 mb files.

> >

>

> I do not thing that 1000MB or even 500 MB is a good datafile size for

> 0.5 TB data warehouse. Maybe you should consider larger datafiles,

> because 500 (1000) data_files would be a nightmare to administer.

> You can have 5000MB data files (100 of them), but you should carefully

> plan your partition policy for your biggest tables to improve read

> performance.

> You must begin with internal analysis and after that, you can move to

> deciding data files layout.

> You'll need to know your enemy (the biggest tables), before throwing

> out numbers like 500 MB, 1000 MB.

> Maybe you have been already doing that, but from your question it was

> unsure.

>

> --

> _________________________________________

>

> Dusan Bolek, Ing.

> Oracle team leader

>

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