Re: Import performance.

On large imports, I found that turning off archive mode will save the most time.

Here's the trick, if you have the luxury.

We run everything redundant, including disks. Before attempting the import, put in a third shadow set, and turn off archiving. When done with the import, do a normal shutdown, and break the 3rd shadow set (you can use that for cold backup!) and then turn archive mode back on....

With large imports, most of the performance hit is i/o due to archive mode.

Doug

Linda Montgomery wrote:
>
> There are several changes we make to increase import speeds. Here is our little
> checklist of things to check/change before a big import. Afterwards we put
> everything back like it was.
> 1. Make sure redo logs are large enough & that there are enough groups. Try to
> keep log switches at least 3 minutes or more apart. We have been increasing
> logfile size to 30M minumum ( a size that worked for our environment) if
> smaller than that in production.
> 2. Place each logfile on a seperate drive (or ping pong between drives) to
> eliminate contention.
> 3. Set db writers = # of disk drives * 2
> 4. Set init.ora parameter checkpoint_process = true
> 5. Verify log_simultaneous_copies is corret for the # of processors, or remove
> parameter if on a single cpu machine.
> 6. Check for adequete rollback & temp tablespace sizes & that their initial &
> next extent will allow them to grow to the maximum value.
> 7.Be sure to use commit=y for large tables
> 8. Increase size of init.ora parameter log_buffer to 1,024,000
>
> Linda
> montgolh_at_jmu.edu
>
> MotoX wrote:
>
> > Correct, only EXPORT supports DIRECT.
> >
> > And remember to take a *backup* after recreation of the indexes, unless you
> > want to go through the whole procedure again should you suffer media
> > failure...
> >
> > MotoX.
> >
> > Murali Kazhipurath wrote in message <362d879c.0_at_blushng.jps.net>...
> > >From what I have understood, DIRECT PATH only works with EXPORT. Here are a
> > >few tips:
> > >
> > >1. Drop all Indexes.
> > >2. Import without indexes using the option indexes=n.
> > >3. Rebuild indexes using the UNRECOVERABLE option.
> > >
> > >Hope this helps.
> > >
> > >Murali
> > >murali_at_jps.net
> > >
> > >
> > >xsun1913_at_my-dejanews.com wrote in message
> > ><70ilit$2j0$1_at_nnrp1.dejanews.com>...
> > >>In article <01bdf5d0$fabc77a0$5feaabc3_at_ken-bailey>,
> > >> "Ken Bailey" <Ken.Bailey_at_BLAENAU_GWENT.btinternet.com> wrote:
> > >>> Can anyone give me any guidelines on improving import performace (
> > >>> parameters etc) ?
> > >>>
> > >>>
> > >>
> > >>Use DIRECT PATH when running import; Set buffer to a large number.
> > >>
> > >>
> > >>Xuening Sun
> > >>
> > >>
> > >>
> > >>-----------== Posted via Deja News, The Discussion Network ==----------
> > >>http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
> > >
> > >
Received on Mon Oct 26 1998 - 02:57:31 CST