Re: Advanced Replication Question for Advanced DBAs

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 I haven't tried to use oracle replication since back in the 7.3 days when they were called snapshots. I had numerous problems trying to set up fast refresh snapshots to data-marts off of a centralized data warehouse. We would test it till we were blue in the face and it would all work perfectly... until our huge monthly production refresh took place and every month the same thing would happen - somehow the snapshots got out of sync with the master and thought that a full refresh was required when it was not. We eventually gave up and started ftp'ing flat files to be loaded with sqlldr to all of the data marts.

As to AR, one of my colleagues here went to the AR class least year and even in the classroom setting they were never able to get it to work. This was on 8.0.

My experience with hot standby has not been bad at all. It's worked most of the time. Occasionally the connection between the production and standby databases gets broken and I have to manually recover the standby but this has been rare. When I've had to do it though it's been very simple. Just ftp the missing log(s) and apply all logs up to the most recent one. Then start managed recovery again and they're back in sync. I have a cron job that queries v$loghist on both databases every hour to make sure they're in sync and if not it emails me.

  dmeng_at_focal.com wrote:
Greetings,
I am evaluating different High Availability options for our shop and I am kind of undecided between Hot Standby and Advanced Replication(AR) : It seems to me that Multi-master replication is a much better choice for us -- all we need is to set up two master sites with one of them read-only. Also it seems to be fairly easy to set up using Replication Manager ( it is up and running in my test instances after only one day's work including reading the docs). This will prevent conflicts and give us the extra benefit of a reporting instance. Hot Standby, on the other hand, might take longer to set up and does not provide read capability ( yes, I know in 8i you can open for read, but it does not apply the logs when it is in readable mode, right? ). So what caveats are associated with AR that drive people to use Standby at all? I know there might be problems with AR if the transaction volume is high. The databases here typically generates less than 100M of redo everyday.

TIA Dennis Meng
Database Administrator
Focal Communications
847-954-8328

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<P> I haven't tried to use oracle replication since back in the 7.3 days when they were called snapshots. I had numerous problems trying to set up fast refresh snapshots to data-marts off of a centralized data warehouse. We would test it till we were blue in the face and it would all work perfectly... until our huge monthly production refresh took place and every month the same thing would happen - somehow the snapshots got out of sync with the master and thought that a full refresh was required when it was not. We eventually gave up and started ftp'ing flat files to be loaded with sqlldr to all of the data marts.</P>

<P>As to AR, one of my colleagues here went to the AR class least year and even in the classroom setting they were never able to get it to work. This was on 8.0.</P>

<P>My experience with hot standby has not been bad at all. It's worked most of the time. Occasionally the connection between the production and standby databases gets broken and I have to manually recover the standby but this has been rare. When I've had to do it though it's been very simple. Just ftp the missing log(s) and apply all logs up to the most recent one. Then start managed recovery again and they're back in sync. I have a cron job that&nbsp;queries v$loghist on both databases every hour to make sure they're in sync and if not it emails me.<BR></P>

<P>&nbsp; <B><I>dmeng_at_focal.com</I></B> wrote: <BR>

<BLOCKQUOTE style="BORDER-LEFT: #1010ff 2px solid; MARGIN-LEFT: 5px; PADDING-LEFT: 5px">Greetings,<BR>I am evaluating different High Availability options for our shop and I am<BR>kind of undecided between Hot Standby and Advanced Replication(AR) :<BR>It seems to me that Multi-master replication is a much better choice for<BR>us -- all we need is to set up two master sites<BR>with one of them read-only. Also it seems to be fairly easy to set up using<BR>Replication Manager ( it is up and running in my test instances after only<BR>one day's work including reading the docs). This will prevent conflicts and<BR>give us the extra benefit of a reporting instance. Hot Standby, on the<BR>other hand, might take longer to set up and does not provide<BR>read capability ( yes, I know in 8i you can open for read, but it does not<BR>apply the logs when it is in readable mode, right? ).<BR>So what caveats are associated with AR that drive people to use Standby at<BR>all? I know there might be!

 problems with AR if the transaction volume is<BR>high. The databases here typically generates less than 100M of redo<BR>everyday.<BR><BR>TIA<BR><BR>Dennis Meng<BR>Database Administrator<BR>Focal Communications<BR>847-954-8328<BR><BR><BR><BR>-- <BR>Please see the official ORACLE-L FAQ: http://www.orafaq.com<BR>-- <BR>Author: <BR>INET: dmeng@focal.com<BR><BR>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051<BR>San Diego, California -- Public Internet access / Mailing Lists<BR>--------------------------------------------------------------------<BR>To REMOVE yourself from this mailing list, send an E-Mail message<BR>to: ListGuru@fatcity.com (note EXACT spelling of 'ListGuru') and in<BR>the message BODY, include a line containing: UNSUB ORACLE-L<BR>(or the name of mailing list you want to be removed from). You may<BR>also send the HELP command for other information (like subscribing).</BLOCKQUOTE><p><br><hr size=1><b>Do You Yahoo!?</b><br>


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