October 7, 2009 at 9:16 am
We are working on a Proof-Of-Concept for an DR configuration, including Oracle front-end databases and SQL Reporting databases. The configuration is:
Production:
Oracle Prod DB, replicated to SQL Instance (using SQL Replication).
DR:
Oracle - Oracle replication (Logical Standby)
Oracle DR DB, replicated to SQL Instance (using SQL Replication).
Due to the data volume, we cant have a cold SQL DR instance - the recovery time is around 24 hours, and we cant mirror / replicate / transaction-log DR from SQL - SQL because the SQL/Oracle Replication wont pick up if we lose the Oracle Productin database and have to fail over to the Oracle DR database (among several other failure scenarios that also wont work).
For the DR Oracle - SQL replicatino we are using a different Oracle Schema than the Production Replication due to issues wth the Oracle Logical standby failing when I try to initiate the SQL Replication on the DR database.
The issue is:
The DR Oracle - SQL Replication is not working, data is not coming across to SQL. I have a process that compares the live SQL data to the DR SQL data, and differences accumulate over time, no updates seem to be applied at the SQL DR instance. all other data sets are in synch (Oracle Prod, SQL Prod and Oracle DR). Running the Snapshot agent on the publications and re-initializing the subscriptions brings the SQL DR instance back to currency with Oracle DR. Replication Monitor on the SQL DR instance shows no errors. How do I determine where the issue is?
TIA for any help ...
October 19, 2009 at 10:54 am
Replication is the process whereby data is copied between databases on the same server or different servers connected by LANs, WANs, or the Internet.
Microsoft SQL Server replication uses a publisher, distributor and subscriber metaphor.
Publisher is the server or database that sends its data to another server or database.
Subscriber is the server or database that receives data from another server or database.
Distributor is the server that manages the flow of data through the replication system. This server contains the distribution database.
Publisher contains publication/publications. Publication is a collection of one or more articles that is sent to a subscriber server or database.
Article is the basic unit of replication and can be a table or a subset of a table.
Subscription is the group of data that a server or database will receive.
There are push and pull subscriptions.
Push subscription is subscription when the publishing server will periodically push transactions out to the subscribing server or database.
Pull subscription is subscription when the subscribing server will periodically connect to the distribution database and pull information.
The Distribution database is a system database, which is stored on the Distributor and does not contain any user tables. This database is used to store snapshot jobs and all transactions waiting to be distributed to Subscribers.
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