Re: Disaster planning advice needed

From: Peter Sharman <psharman_at_us.oracle.com>
Date: Wed, 03 Feb 1999 13:05:32 -0800
Message-ID: <36B8BA1C.50E781D8@us.oracle.com>

Greg

Replication is not really designed as a disaster recovery scenario. It can be used for that, but there are some issues that you need to be aware of when doing it:

Depending on the frequency of data transfer, you will appear to lose more or less data. The reason I say appear is that the data will still be in the queues on the primary site, and if the issue is one which is resolved without recovering, when the primary site becomes available again you will receive the queued data.
Following from 1, you need to train your users not to rekey data that appears to be lost.
If the replication is bi-directional, failure to the secondary site means that any data stored in the queues on the secondary site will stay there until the primary becomes available again.
If you need to perform point in time recovery for the primary, you will need to do likewise to the secondary.

There are other options you should look at as well. Offsite backup may be sufficient. Alternatively, you could use standby database from 7.3 on, OPS as part of a solution (doesn't protect against site failure), geo-mirroring if you have lots of money, or something like SRDF from EMC (Oracle only supports synchronous mode writes here though, so you should expect a performance hit on your primary site).

HTH. Pete

"Greg C." wrote:

> Hello, Could you please give me some guidance as to how I should approach
> disaster planning. I am about to begin a new position with a new company.
> I will be working on designing a disaster recovery plan. My new company
> is trying to use multimaster replication for this. The failover will only
> become available to users when the primary fails. No users will be
> attached to the failover while the primary is active. In the event of a
> failure the failover site is to become the primary. The fail over site does
> not reside in the same location as the primary db.
>
> My opinion is that we should use a hot backup site for this scenario. Can
> you also comment about this plan?
>
> How are others approaching this situation? What are the trade offs
> between a hot standby and multimaster replication? What is the downside to
> either approach?
> Are there any third party tools to help in maintaining a hot standby
> database?
>
> Thank you for your help.

Regards

Pete

Peter Sharman                              Email: psharman_at_us.oracle.com
WISE Course Development Manager            Phone: +1.650.607.0109 (int'l)
Worldwide Internal Services Education               (650)607 0109 (local)

San Francisco

"Controlling application developers is like herding cats." Kevin Loney, ORACLE DBA Handbook
"Oh no it's not! It's much harder than that!" Bruce Pihlamae, long term ORACLE DBA

Received on Wed Feb 03 1999 - 15:05:32 CST