Re: DB mirroring

From: Daniel Fink <Daniel.Fink_at_Sun.COM>
Date: Tue, 13 Jul 2004 08:55:46 -0600
Message-id: <40F3F7F2.5080301@sun.com>

Morten,

I'll preface this by saying I'm not a replication/standby/DG expert. But I have dealt with this type of situation before, unfortunately (or perhaps fortunately) I was not around to see what was actually implemented.

RAC requires shared storage. 1 database -> Many instances.
This is probably your best option. Data Guard is intended to be used in this situation. IIRC, you will need manual intervention, there will be downtime and there *may* be loss of data.

Other options:
1) mirror DML/DDL...sounds like a trigger or Quest's Shareplex. If it is a trigger, you are talking about maintaining a db_link and having a distributed database. Requiring the commit on the remote database (only way to "guarantee" sync) will be problematic, introduce additional points of failure and will probably be a performance killer. This database sounds far too dynamic for this.

2) Oracle streams? My impression is that this product may offer some assistance. I've never used it, but have read papers/presentations by some excellent non-marketing folks.

Good luck.

Daniel Fink

Morten wrote:
> Hi.
>
> I have two servers A and B. They are physically separated, and are only
> allowed to communicate over LAN (ie. no shared storage).
>
> If one server dies, clients should access the other, so they need to be in
> sync. So far I've found the following options for making a fail-over
> system for Oracle (9i2 BTW):
>
> 1. RAC - this requires shared storage as far as I can tell from the
> whitepaper.
>
> 2. Oracle Data Guard w. primary/secondary servers. Requires operator
> intervention upon failure at the primary host. If this is acceptable,
> it's still not an optimal solution as we can expect lots of
> structural changes to the DB (new tables, altered tables, new/dropped
> indexes etc).
>
> What other options are there? Is there a "mirror all ddl+dml operations on
> this DB to that DB" option?
>
> Any tips greatly appreciated,
>
> Morten
>
>
>
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Received on Tue Jul 13 2004 - 09:54:33 CDT