RE: How much time can save using _disable_logging on 10g
- To: "Juan Carlos Reyes Pacheco" <juancarlosreyesp@xxxxxxxxx>
- Date: Tue, 11 Oct 2005 13:03:31 -0400
Just go all the way with it.
Some of this information was given to me by friends on this list.
I believe Connor gave me this info on "_wait_for_sync".
Who ever did it (correctly) came with a strong warning.
PS I did not test "_wait_for_sync".
=================
Set init.ora parameter LOG_ARCHIVE_START = FALSE
*&* alter database noarchivelog;
Set init.ora parameter _disable_logging = TRUE (Warning, this could be
dangerous and unrecoverable in failure.
Backup immediately after import - * Redo records (to disk) will NOT be
generated (redo WAS generated in the log buffer.) [Even with
_disable_logging you still "switch" logs when they get "full"])
Set init.ora parameter _wait_for_sync = FALSE (Warning, this could be
dangerous and unrecoverable in failure.
Backup immediately after import - _wait_for_sync: Wait_for_sync is an
oracle generic parameter which, when set to false, will allow the system
to complete commits without waiting for the redo-log buffer flushes to
complete.)
Make redo logs enormous; 500MB, 1GB, etc.
=================
Chris Marquez
Oracle DBA
-----Original Message-----
From: Marquez, Chris
Sent: Tuesday, October 11, 2005 12:29 PM
To: 'Juan Carlos Reyes Pacheco'
Cc: mcdonald.connor@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: How much time can save using _disable_logging on 10g
>>Can you tell me please how much time you saved
I had to dig through my notes...I don't have a memory for this stuff
...that's why I take notes.
This is from my own email to my co-workers;
>> I was able to load theses TABLEs in about 24 to 32 minutes.
>> Below are my EXPort and IMPort parameters.
>> Also, I tried using the Oracle parameter; "_disable_logging = TRUE"
>> ...it seemed to have a 15% - 25% time improvement...18 minutes.
hth
Chris Marquez
Oracle DBA
-----Original Message-----
From: Juan Carlos Reyes Pacheco [mailto:juancarlosreyesp@xxxxxxxxx]
Sent: Tuesday, October 11, 2005 12:07 PM
To: Marquez, Chris
Cc: mcdonald.connor@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: Re: How much time can save using _disable_logging on 10g
Thanks Chris, I agree with you, a simple shutdown immediate crashed my
test database too, but anyway is interesting to know its limitations.
Can you tell me please how much time you saved :) only for statistics.
when migrating.
Thanks in Advance.
On 10/11/05, Marquez, Chris <cmarquez@xxxxxxxxxxxxxxxx> wrote:
>
>
>
> >>shutdown abort with _disable_logging and you'll see some interesting
> consequences
>
> Ahhhh yes we conversed on this topic a while back. I used
_disable_logging
> for migration purposes after a lot of TEST my process.
> I kept wondering why my test db was crashing hard...we had some disk
> issue at the time, so that seemed the culprit.
> Turns out I kept leaving my TEST db up with _disable_logging enabled
> during server reboots...it did not come back happily
>
> A great and very, very challenging recovery filled with undocumented
> parameters that rendered my TEST database un-supported.
> I was able to recover sometimes, but others not.
> Think I was "bumping scn's" and allowing reset log corruption.
> You have not lived until you have recovered a database this
way...nasty!
> :o)
> Also, learned and documented the "clean way" to stop using
> _disable_logging and put my db back in archive log mode.
>
>
> Sorry, "yes" _disable_logging saved time during my migration (at the
> risk of loosing it all on the *new* server, but not on the old
server).
>
> Chris Marquez
> Oracle DBA
>
> ________________________________
> From: oracle-l-bounce@xxxxxxxxxxxxx
> [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
> On Behalf Of Connor McDonald
> Sent: Monday, October 10, 2005 11:08 AM
> To: oracle-l@xxxxxxxxxxxxx
> Subject: Re: How much time can save using _disable_logging on 10g
>
>
> shutdown immediate is still a clean shutdown.
>
> Try shutdown abort with _disable_logging and you'll see some
> interesting consequences
>
> hth
> connor
>
>
>
> --
> Connor McDonald
> ===========================
> email: connor_mcdonald@xxxxxxxxx
> web: http://www.oracledba.co.uk
>
> "Semper in excremento, sole profundum qui variat"
--
Oracle Certified Profesional 9i 10g
Orace Certified Professional Developer 6i
8 years of experience in Oracle 7,8i,9i,10g and developer 6i
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