Re: Oracle Data Guard

Hi Vijay,

I've done around 20 DG installations at different sites, using Linux, Solaris, AIX and W2K.

High speed network isn't always what you need, low latency might be more important. I've set up a DG environment between Kuala Lumpur and Rotterdam, using a 128KB line. This wasn't for standby reasins, but was about database consolidation. As long as the daily Archive Log could be done, everything was OK.

For maximum availability/protection mode you get synchronous writes. Latency counts very much. See also DocId 233650.1 on Metalink, Titled 9i Data Guard Complete Reference. It actually contains a list of interesting Data Guard publications on metalink.

Force logging mode is required for Logical Standby. I agree with Tanel, LSB isn't for production yet. However, in some situations it might be usefull for a reporting database, as long as you do not rely on the standby part. Create a PSB for that purpose.

On one site, with a long distance PSB (> 100 km between datacenters), with requirements about Zero Data Loss, I advised to setup a PSB/maximum availabilty mode locally, and a remote PSB in max. performance mode. This minimizes the chance of data loss, and affects performance as little as possible.

Regards, Carel-Jan

• There will allwasy be another 10 last bugs --

At 07:19 8-12-03 -0800, you wrote:
> > Hi All,
> >
> > can any one let me know kindly the following info.
> >
> > 1) Has any one used the Oracle 9i Data Guard?
>
>Yes, physical standby and successfully.
>
> > 2) If yes then, is there any performance impact on
> > Target/Source server database.
>
>Your database has to be in archivelog mode, but when you are thinking such
>solutions as DG, then you probably are already running archivelog anyway.
>
>If you run in maximum protection or maximum availability, yes there is. The
>impact depends mainly on network connection between primary and standby(s)
>and the speed of redolog disks. You could tune these by using faster
>network, enabling jumbo frames and SDU size if using Gbit ethernet, also
>setting lgwr and log apply processes priority higher than others.
>
> > 3) any drawbacks using Data Guard.
>
>You should set your database or critical tablespaces to force logging mode
>in order to transfer all changes to standby in physical standby. That means,
>performance improvements which take advantage of nologging operations (such
>insert append nologging etc), will not run that fast anymore.
>In logical standby, I think there's no such requirement, but I don't
>recommend you to use logical stby yet, it's more like a prototype currently,
>not exactly a working product.
>
>Tanel.
>
>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>--
>Author: Tanel Poder
> INET: tanel.poder.003_at_mail.ee
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Carel-Jan Engel
  INET: cjpengel.dbalert_at_xs4all.nl

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