A hot standby database is a second running database that is created from and transactionally consistent with the primary or master database. Data modifications that are made to the master database are made simultaneously to the secondary database. The secondary database is sometimes referred to as a hot standby database because it is available immediately to pick up application processing if the primary database system fails. It can be used to implement a mission-critical and disaster recovery functions. The question arises as to whether the standby database can be a part of replication, either as source or target.
N.A.
The Oracle hot standby database is in sync with its source at all times. This is achieved by applying the redo logs generated from source database. However, it is not open during all this time. The only time it is opened is when one is ready to failover to hot standby. At that instant it becomes the source database. This prevents it from being used as a source or target in a replication environment. A hot standby database can never assume a role of source database for Shareplex since it is not in an open state. When finally it is opened, it is done with resetlogs which will make it unusable as source. This applies to SharePlex versions earlier than 8.x.
As for its use as target, the procedure is very cumbersome and hence it can be said that for almost all practical purposes it cannot serve as a target either. Once a hot standby is opened as a regular database instance, it can serve as a source or target in a replication.
ADDENDUM:
The following applies to SharePlex version 8.x and up:
It is possible to replicate from an Oracle hot standby due to some additional parameters that can instruct SharePlex to read from archive redo logs, among others. The following steps are involved on the source whereas on target the steps for installing and configuring SharePlex are same as for a regular Oracle database as the target cannot be a physical standby:
1. Install SharePlex on Physical Standby box
2. Create a TNS entry on Physical Standby box that points to Production Database (source)
3. Run ora_setup – While running ora_setup provide following info:
a. ORACLE_SID: Source SID (Standby SID is also same as source)
b. ORACLE_HOME – Standby ORACLE_HOME location
c. When it asks for a user with DBA privs, give SYSTEM and in password give <password>@TNS (TNS created in step 2)
d. When is prompts for SPLEX user creation, give user name (SPLEX) and in password again give <password>@TNS
4. Start sp_cop
5. In sp_ctrl give following 3 params:
a. Set param SP_OCT_READ_ARC 1 (This parameter instructs ACTIVATION to read from archive in place of redo)
b. Set param SP_OCT_CK_LOC_FIRST 1
c. Set param SP_OCT_ARCH_LOC <location_of_archive_logs> (The location where DG is putting the source archive files on Standby Server)
6. Create config file and activate same
Here are the description of the above parameters as taken from Reference Guide or Release Notes:
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