RE: Question for Dataguard users

From: <japplewhite_at_austinisd.org>
Date: Wed, 27 Jul 2011 16:17:03 -0500
Message-ID: <OF0C08A873.A8A80DA5-ON862578DA.007325DD-862578DA.0074EBD7_at_austinisd.org>

We (IT), not Us (DBAs), do control our own LAN / WAN, so it works very easily for us. From what I understand it is relatively trivial to apply / transfer a DNS alias to / from a server so maybe the other IT shop won't balk. We (DBAs) do control the DB Service_Names, so that part is no problem.

Yes, if we have a DB of SID=db01 on host srvr01, we'll have a DNS alias of db01 applied to server srv01. The entry in any TNSNames.ora would have HOST=db01 and Service_Name=db01. If we also had a Service_Name of ABC on the db01 database, we'd have a DNS alias abc on server srv01. Entries in TNSNames.ora files would have HOST=abc and Service_Name=abc.

The caveat with Standbys is to use HOST=srv01 - the real hostname - in the Listener.ora file. I found that out the hard way when I had the DNS alias as HOST in a Primary Listener.ora file. When the DNS alias was moved to the Standby and I went to shut down the Listener on the Primary, the Listener on the Switched Over Standby went down. The lsnrctl utility obediently followed the DNS alias as well and shut that Listener down remotely. Now all the Listener.ora files use HOST=<TheRealHostname>.

It may seem complex at first, but the flexibility and not having to fool around with edits to TNSNames.ora files are well worth the setup.

Jack C. Applewhite - Database Administrator Austin I.S.D. - MIS Department
512.414.9250 (wk) / 512.935.5929 (pager)

From: "Storey, Robert (DCSO)" <RStorey_at_DCSO.nashville.org> To: <japplewhite_at_austinisd.org>, oracle-l-freelists <oracle-l_at_freelists.org>
Date: 07/27/2011 03:22 PM

Subject:        RE: Question for Dataguard users
Sent by:        oracle-l-bounce_at_freelists.org

Excellent approach. Not sure if it will work for me since our department does not have any control over out network. We (the IT shop) have to work through the city IT shop to get anything network wise done. Still doable, just adds a layer of futzing to the issue.  

So what do you put in the HOST field of the tnsnames? So, you have a database on host ABC that has a database of DB01. You create a DNS entry called DB01 that points to host ABC? So, in the HOST field do of tnsnames you would put DB01?  

Thanks  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of japplewhite_at_austinisd.org Sent: Wednesday, July 27, 2011 3:06 PM
To: oracle-l-freelists
Subject: Re: Question for Dataguard users  

Robert,

We handle that via DNS aliases. We never use the actual hostname in any TNSNames.ora file or JDBC or other connect string. We have our Sys Admins add a DNS alias for every database on a server. It's exactly the same as the Service_Name for the database. We may have several Service_Names per actual database. There is a DNS alias for each of those Service_Names on the host server. That allows us to start a new Vendor App as a schema in an existing database (with its own Service_Name and host DNS alias) and see if it comes to eventually need its own database. If so, or we just want to move the schema, we move the Service_Name and DNS alias to the new DB and server and all connect strings continue to work.

The same thing works for Switchovers / Failovers to Standbys from Primarys. When we do a Switch / Failover, we just prep the DBs, have the Sys Admins switch the DNS aliases. Then all Clients can reconnect to the new Primary. No muss, no fuss. Works great.

Jack C. Applewhite - Database Administrator

From:        "Storey, Robert (DCSO)" <RStorey_at_DCSO.nashville.org> 
To:        oracle-l-freelists <oracle-l_at_freelists.org> 
Date:        07/27/2011 12:44 PM 
Subject:        Question for Dataguard users 
Sent by:        oracle-l-bounce_at_freelists.org 

Okay, have a question for the dataguard users. Probably more for the non-RAC folks than anything.   

My setup is a primary and a single physical standby.   

In the event of a switchover, all user connections are broken and the switch occurs. Then users have to reconnect.   

But, I’m looking for the best way to structure the TNSNAMES file. I’m probably over thinking this, but, there has to be a way to create both entries for both servers in the file, but only have them use the production one. Something tickles my brain from way back that it will run the TNS list in order looking for a connection.   

Just curious how others have set up their files.   

Thanks

--
http://www.freelists.org/webpage/oracle-l

Received on Wed Jul 27 2011 - 16:17:03 CDT