Re: How to resize redo logs

OK: a practical question!

1. You can' t resize them. All you can do is drop the old ones, and create new ones of a bigger size (though if you've any sense you will create the new ones first, and THEN drop the old ones)

2). Create new ones: alter database addlogfile group x '/blah/blah/blah.rdo' size 150Gb (we can dream!)

3) Drop old ones : alter database drop logfile group 1;

4) Subject to the proviso that you can't drop a log group which is current or active: v$logfile tells you what's what, and 'alter system switch logfile' makes a group active, and a previous group inactive (if you give it long enough).

Regards
HJR "Mo" <ranamo_at_mailbox.bellatlantic.net> wrote in message news:3A79FBB6.BB471CD9_at_mailbox.bellatlantic.net...
> Thank you guys for the tips, but I still not sure how to resize a redo log
 files.
>
> just to be clear I am talking about the redo log files.
>
> My redo log file is 1 meg in size and I want to increase it to 5 meg.
>
> Thanks
> Mo
>
>
> > You can also query the database to determine how often the redo logs
> > are switching. There are several flavors of the script below, but this
> > one will calculate the average log switches per day.
> >
> > -- avg redo switches per day
> > select round(avg(count(*)))
> > from v$loghist
> > group by to_char(first_time,'J');
> >
> > mreeves
> >
> > On Fri, 2 Feb 2001 08:02:13 +1100, "Howard J. Rogers"
> > <howardjr_at_www.com> wrote:
> >
> > >They should be as big as are needed to get log switches happening at
 the
> > >"right" interval.
> > >
> > >Huge log files will take ages to fill, and you will therefore log
 switch
> > >infrequently. Since there is a major checkpoint at each log switch,
 that
> > >means you avoid having one hell of an i/o fest. Performance therefore
 goes
> > >up a bit. Since Instance Recovery means Oracle replays all
 transactions
> > >since the last checkpoint, however, then huge log files mean longer
 Instance
> > >Recoveries.
> > >
> > >Tiny log files will fill rapidly, and will therefore switch like
 crazy -lots
> > >of checkpoints, poor performance, but good Instance Recovery times.
> > >
> > >Your mission is to find somewhere along that spectrum where you can be
> > >happy. The usual 'rule of thumb' that a lot of DBAs adopt is to
 arrange for
> > >the files to be big enough that they switch every half-hour to an hour,
 on
> > >average. But that may well not be what is suitable in your particular
 case.
> > >
> > >You can check how often you are log switching by checking the Alert
 Log.
> > >Messages such as "Thread 1 advanced to Log Sequence 15634" indicate a
 log
> > >switch.
> > >
> > >If you ever see a message to the effect that "Thread 1 unable to
 advance to
> > >Log Sequence 15635", then it means you haven't got *enough* redo log
 groups
> > >(the size of them having little or no bearing on that particular
 message).
> > >
> > >Regards
> > >HJR
> > >
> > >
> > ><MAbbouchi_at_IITRI.ORG> wrote in message
> > >news:DD42667CBCE4D3119D0700104B95123F3016CA_at_abmail.iitri.org...
> > >> How to resize redo logs and is there a special consideration to be
 aware
 of?
> > >>
> > >> Thanks
> > >> Mo
> > >>
> > >> --
> > >> Posted from nat05.IITRI.ORG [205.167.170.5]
> > >> via Mailgate.ORG Server - http://www.Mailgate.ORG
> > >
> > >
>
Received on Fri Feb 02 2001 - 07:26:56 CST