Re: Multiplexing redologs - is there still need for it?

"Sybrand Bakker" <gooiditweg_at_sybrandb.demon.nl> wrote in message news:7h2450t4478a324gt0eq7aii7k6sic4ted_at_4ax.com...
> On 12 Mar 2004 08:15:57 -0800, pagesflames_at_usa.net (Dusan Bolek)
> wrote:
>
> >Today, I have run into an interesting discussion. The question was if
> >there is a need for multiplexing redologs by database (as suggested in
> >Admin manual) if this data are already mirrored (using RAID, disk
> >arrays mirrors, Data Guard, SRDF etc.).
> >I'm somehow paranoid, so I proposed tu use multiplexing, while other
> >party stated that these bytes are already stored on eight different
> >locations. That's sounds sensible, but I remember the issue a long
> >time ago in a company far far away, where one of two multiplexed
> >control files got corrupted and (of course) copies on both mirrored
> >disc vere identical (means corrupted), second redo log on different
> >volume group was OK. So in this case we would been doomed if these
> >redologs weren't multiplexed.
> >What's the opinion on this topic in the newsgroups? Preferably with
> >some technical explanation.
>
>
> Mirrored drive: Oracle will queue 1 write request. If that write
> request fails, your database is toast.
> Multiplexed redologs: Oracle will queue 2 write requests. As long you
> don't put the members on 1 single drive, it is very unlikely *both*
> requests fail.
>
>
> --
> Sybrand Bakker, Senior Oracle DBA

By toast, did you mean the database will come to a complete stop or unusable/unrecoverable? Received on Sun Mar 14 2004 - 11:26:16 CST