Re: from Non-Archive-Mode to Archive-Mode

Raj,

The alert log shows the log switching, which is the indicator to how much redo has been generated. Another method is to see this figure from v$log_history. The objective is to identify the rate of redo switch and therefore, the rate of redo generation. The original poster asked how to estimate the archive log generatoin and I answered that.

However, a slip was the inclusion of log_checkpoints_to_alert, which is admittedly not necessary. However, the content of the post was factually correct. Kirti, in a private mail, was kind enough to let me know of the possible confusion and I appreciate that. Hope that clarifies the response.

Arup

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Tuesday, January 21, 2003 10:50 AM

>
> Arup,
>
> My initial reaction was that you were suggesting setting the parameter to
> know the frequency of your log switches. But now to clearly understand
your
> point of view, and for my curiousity, how does one derive the amount of
> redo log generated in bytes using the SCN Numbers?
>
> Thanks
> Raj
>
>
>
>
>
>
> "Arup Nanda"
> <arupnanda_at_ho To: Multiple recipients of
list ORACLE-L <ORACLE-L_at_fatcity.com>
> tmail.com> cc:
> Sent by: Subject: Re: from
Non-Archive-Mode to Archive-Mode
> root_at_fatcity.
> com

>
>
> January 17,
> 2003 05:54 PM
> Please
> respond to
> ORACLE-L
>
>
>
>
>
>
> Raj,
>
> I'm afraid I don't understand. Was that incorrect in some way? The alert
> log will contain information when the redo logs switch, e.g.
>
> Thread 1 advanced to log sequence 38451
> Current log# 1 seq# 38451 mem# 0: /x12/oradata/IDW1/redo01a.dbf
> Current log# 1 seq# 38451 mem# 1: /x22/oradata/IDW1/redo01rba.dbf
> Fri Jan 17 17:46:49 2003
> Completed checkpoint up to RBA [0x9633.2.10], SCN: 0x0000.4f7c86d7
> Completed checkpoint up to RBA [0x9632.2.10], SCN: 0x0000.4f7c86d5
> Fri Jan 17 17:46:50 2003
> Beginning log switch checkpoint up to RBA [0x9634.2.10], SCN:
> 0x0000.4f7c86d9
> Thread 1 advanced to log sequence 38452
> Current log# 3 seq# 38452 mem# 0: /x12/oradata/IDW1/redo03a.dbf
> Current log# 3 seq# 38452 mem# 1: /x22/oradata/IDW1/redo03b.dbf
> This will help identify the frequency of log switch and an indicator to
the
> amount of redo generated. The question was how to estimate the amount of
> archive log generation and that was one way. So, is that wrong? Please do
> correct me if you think so. Of course the information can be readily
> obtained from v$log_history; but then again, that's another way, not the
> only way.
>
> Arup
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Friday, January 17, 2003 1:25 PM
>
> >
> > Arup,
> >
> > From your past replies to the list, I am surprised to hear you say this.
> > "If you have placed the init.ora parameter log_checkpoints_to_alert set
> to
> > TRUE, then your alert log file will have lines when the redo log group
> > switch fom one to the other."
> >
> > Regards
> > Raj
> >
> >
> >
> >
> >
>
> > "Arup Nanda"
>
> > <arupnanda_at_ho To: Multiple recipients of
> list ORACLE-L <ORACLE-L_at_fatcity.com>
> > tmail.com> cc:
>
> > Sent by: Subject: Re: from
> Non-Archive-Mode to Archive-Mode
> > root_at_fatcity.
>
> > com
>
> >
>
> >
>
> > January 17,
>
> > 2003 09:35 AM
>
> > Please
> > respond to
>
> > ORACLE-L
>
> >
>
> >
>
> >
> >
> >
> >
> > Murat,
> >
> > The estimate of amount of space for archive logs come from your redo log
> > switch. If you have placed the init.ora parameter
> log_checkpoints_to_alert
> > set to TRUE, then your alert log file will have lines when the redo log
> > group switch fom one to the other. That will give you a rough idea of
the
> > time it takes to fill up a redo log. If you are using archiving, the
redo
> > log has to be written to disk. In any one given day, you can then
> calculate
> > the archive log generation.
> >
> > Then comes how you want to back it up and clean up the space. If you
have
> a
> > process running that will scan for archive logs; back them to tape and
> then
> > delete it, then you have to figure out how often this process runs and
> how
> > much archive log stays on the disk before getting deleted.
> >
> > Changing the log mode of the tablespace level does not change teh redo
> log
> > genration in most cases. If you define a tablespace or an object as
> > nologging, only a few operations like ALTER TABLE .. PARTITION, ALTER
> INDEX
> > REBUILD, direct load are not logged, all others are. And in any case the
> > system tables are always logged.
> >
> > HTH.
> >
> > Arup
> >
> > ----- Original Message -----
> > To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> > Sent: Friday, January 17, 2003 5:08 AM
> >
> >
> > > Hi,
> > >
> > > how can I calculate/estimate the extra disk space I'll need if I
> > > change the log mode from non-archive-mode to archive-mode. I want to
> > change
> > > the log mode of all my objects. Do I need to do this one-by-one or is
> it
> > > enough if I change the log mode of my tablesapces?
> > >
> > > Thanks in advance
> > >
> > > Murat
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author:
> INET: Rajesh.Rao_at_jpmchase.com
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Arup Nanda
  INET: arupnanda_at_hotmail.com

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