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RE: options for read only mirror with 10g SE or SE One

From: Mark W. Farnham <>
Date: Tue, 28 Sep 2004 09:50:50 -0400
Message-ID: <>

Manual standby has worked just fine since at least 6.0.36. (Earlier than about then certain race conditions on SMP systems could leave you with corrupt redo logs and no documented way to verify them to know that you should reinstantiate.) Oracle made it into a product much later after they figured that out, along with the complications that homegrown solutions required such as being very careful about adding files and new tablespaces and issues such as whether to allow unlogged actions (which were not an issue in 6.0.36, anyway.)

When Oracle indicated that they did not "support" standby databases at those earlier versions, it was indeed pointed out nearly immediately that a standby configuration was nothing more nor less than a recovery, and the question was asked whether Oracle was de-supporting recovery from hot backups.

Clarification was made that getting individual manual standby strategies correct was not generally supported, and support did not cover getting free consulting in this regard, but physical recovery was most certainly NOT desupported. License issues regarding the recovery machine were not generally addressed until much later, probably when standby recovery became an official feature with more robust built in support for keeping it "right."

I'm not sure who did it "first." I do remember hearing "but you're only allowed to do that with support from Oracle Consulting" some number of years after I had considered it a routine way to support rapid recovery and the creation of databases (cancel recovery, copy, startup with rename open resetlogs) as a convenient frozen image for decision support and loading time series information into long term data stores (warehouses, marts, etc.).

At this writing, though, I believe that Oracle will insist that you must license the additional machine. If you don't plan that the machine would actually be for fail-over, though, I suppose that the additional license for a manual solution could be for quite a modest machine and a small number of users. I'm not sure whether the latest specification for the DataGuard license requires licensing for the same level as the primary machine (albeit with discounts), but a small machine manual standby certainly opens the question of possible major savings. Some folks over the years have negotiated things such as loading an alternate system for verification of the integrity and recoverability of backups, but I think Oracle tends to put a "certain number of times per year" limit in new licenses covering that issue.



-----Original Message-----
[]On Behalf Of Rachel Carmichael Sent: Monday, September 27, 2004 5:43 AM To:; Cc:
Subject: Re: options for read only mirror with 10g SE or SE One

major deletions to not fail the 80% rule..

Manual standby was unsupported in 7.3.4 but was possible as part of "recovery". I learned this by playing when I was testing my recovery scripts.... I was able to just keep handing the recovery process archived logs that were past the date of the crash and Oracle merrily kept up.

I *think* this was documented in a white paper by Lawrence To at that time .

> I'm afraid I don't understand this. You are asking for a read-only
> copy of a database and don't require automated failover. Manual
> standby gives you this and has done since at least version 8 (I
> *believe* since 7.3.4) . It isn't DataGuard but it doesn't sound like
> it needs to be for you (or the cost of DataGuard is unattractive for
> you - which I understand).


Received on Tue Sep 28 2004 - 08:46:30 CDT

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