Re: multiplexing online redo logs

"Richard Foote" <richard.foote_at_bigpond.com> wrote in message news:3QHH9.91092$g9.254443_at_newsfeeds.bigpond.com...
>
> "Pete Sharman" <peter.sharman_at_oracle.com> wrote in message
> news:aslagp01pth_at_drn.newsguy.com...
> > In article <asl6ie$aim$1$8302bc10_at_news.demon.co.uk>, "Alistair says...
> > >
> > >Hi
> > >
> > >Connect as system and try an
> > >
> > >sql> alter system switch logfile;
> > >
> > >then check
> > >
> > >sql> select * from v$log;
> > >
> > >Alistair
> > >
> > >"Uwe" <uwe.embshoff_at_lit.lineas.de> wrote in message
> > >news:3e9b0c3d.0212040707.2667cf27_at_posting.google.com...
> > >> Hello,
> > >>
> > >> I want to multiplex my online redo logs on different disk. I used the
> > >> following command to create an additional member for each of my 3
redo
> > >> log groups:
> > >>
> > >> ALTER DATABASE ADD LOGFILE MEMBER
> > >> '/usr2/oracle/mnt2/oradata/ws93/redo01.log' TO GROUP 1;
> > >>
> > >> To me, this doesn't seem to be enough, because when I change some
> > >> data, these files are not updated. Only the initial redo log files
are
> > >> updated. When I look into v$logfile, they are "invalid". How can I
set
> > >> them to valid?
> > >>
> > >> Thank you!!!
> > >> Uwe
> > >
> > >
> > Perfectly true, but also unnecessary. All that the status of INVALID
> means is
> > that the file is either inaccessible OR that Oracle has not attempted to
> access
> > it yet. While switching log files with an ALTER SYSTEM command will
clear
> this
> > status, so will normal operation of the database causing log switches to
> take
> > place. All you really get by using the ALTER SYSTEM command is a warm
> fuzzy
> > feeling inside. :)
> >
>
> Hi Pete,
>
> The only comment I would add is that assuming you've just seen the light
and
> decided to multiplex your redo logs, the *current* group is still going to
> be "on it's own" as the new member will have no effect until the group is
> written to again.
>
> Performing a redo log switch to the next group means that as of *now*,
your
> generated redo finally has the protection it deserves in that all
subsequent
> redo is multiplexed.
>
> That, and also the fact I can do with all the warm fuzzy feelings I can
get
> ...
>
> Cheers
>
> Richard
>

Richard,

True enough; IMHO, multiplexing of redo is mandatory as of db creation. As far as I can see, *provided* one has a proper backup strategy, the *only* chance of losing data with Oracle is the loss of *all* the online redo.

I like to switch logs about every twenty minutes or so. What does the group think? (Obviously during heavy batch processing this will become much more frequent).

Comments and/or advice welcomed.

Regards,
Paul Received on Thu Dec 05 2002 - 18:24:44 CST