Re: Small Redo Log File Size

Dereck L. Dietz wrote:
> I'm working with an Oracle 10g Version 1.0 datawarehouse database upgraded
> from an Oracle 9i version.
>
> While running the Enterprice Manager and browsing through the performance
> recommendations I came across one which stated the Redo Log Files were too
> small. The size of the current Redo Log Files (3 groups of only 1 file
> each) are only 10MB. Oracle recommended the size of 2GB for the Redo Log
> Files.
>
> Since we've experienced very slow response times the more activity there is
> against the database I think this should be taken seriously. I'm expecting
> resistance - or apathy - when I suggest following this recommendation.
>
> Since I'm not the "official" DBA there (and a contractor to boot) I'd like
> to have as much ammunition as possible to back up my suggestion.
>
> Would it be possible for the more knowledgeable on this group to post about
> the benefits of properly sized Redo Log Files and the pitfalls of improperly
> sized Redo Log Files? I'd like to be able to print them out to use if I
> have resistance to this recommendation.
>
> Thanks.

A more off-the-wall question is, what sort of backups are you doing? (some DW configurations can get by with few, as loads can be redone, or mirroring allows backups to be fast). The reason I ask - perhaps you can get away with more nologging type operations to reduce log generation in the first place. If you have some sort of daily massive loads it may pay to do those nologging and then backup. If you can rebuild the entire warehouse without too much pain it may be possible to noarchivelog (hey, doesn't hurt to ask - well, it might hurt credibility in some places). I always kind of wonder about that enable logging radio button per tablespace...

Sizing redo is a basic DBA function, seeing them so small and not mirrored raises a bit of a red flag for me - I'd be wondering what else is strange. Is the db a red-headed stepchild that no one wants to be responsible for?

hey, good to see Anjo here!

jg

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