Oracle liveSources

Oracle liveSources overview

Prior to Delphix Engine version 4.2, users ran reports against virtual databases (VDBs) that they created with the Delphix Engine. Although this workflow helped them offload the reporting load from production, the data in the VDBs was not updated asynchronously. If users wanted newer data, they had to stop their reporting applications, refresh their VDBs, and resume. In the current release, you can run reports against data that is constantly being updated. There is one live data feed for each source database that is linked as a dSource on the Delphix Engine. You can point your reporting applications to this live feed. Additionally, you will continue to have all existing Delphix functionality from the dSource, such as creating read/write VDBs.

Understanding Oracle liveSources 

Oracle LiveSources leverage native Oracle Active Data Guard technology to keep a standby database up-to-date with changes happening on the source. The standby database is kept open for reads while it applies changes from the source. You can now connect to this standby database for real-time reporting needs. Using Delphix in conjunction with Active Data Guard gives you the ability to get both live up-to-date data and historical points in time from which you can provision virtual databases.

Understanding how to use Oracle liveSources

Oracle liveSources provide a read-only live data stream from Delphix 

You can convert an Oracle dSource to a LiveSource, which is a real-time read-only feed of the linked source. You can access the LiveSource using a JDBC string. Internally, a LiveSource is a standby database instance tracking the Linked Source in real-time managed mode and opened in read-only mode.

Understanding Oracle liveSources with data age and threshold 

One of the important utilities of a LiveSource is that it provides a real-time feed of the linked source. In some instances, due to slow networks or other reasons, the LiveSource might fall behind the linked source that it is tracking. When adding a LiveSource, you can specify a data age threshold. If the LiveSource falls behind the linked source by more than the data age threshold, the Delphix Engine will generate a fault and inform you.

The LiveSource information is displayed on the Status tab. Delphix continuously monitors the standby instance and notifies you of any abnormalities.

• Live Data Status - Indicates that the LiveSource standby database instance is actively receiving data from the source database

• Data Age - Displays the data age of the LiveSource 

You can change the Data Age Threshold at any time by updating the threshold value located on the Configuration > Data Management tab.

Oracle liveSources quickly sync with consistent snapshots

Taking snapshots of a LiveSource is instantaneous since the standby database for the LiveSource is constantly receiving data from the source database and recovering it.  Taking snapshots occurs instantaneously by taking a filesystem level snapshot of the data on the Delphix Engine without requiring an RMAN backup of the source database. All LiveSource snapshots are consistent; as a result, provisioning from LiveSource snapshots is fast, because no database recovery needs to happen.

Oracle liveSources use resync and apply 

Resync is a way to refresh the LiveSource to the current point in the linked source. The following situations require a Resync to be performed:

• There are unresolvable gaps in the log sequence – for example, logs from the source database deleted before the primary database could ship them over to the LiveSource standby.

• The source database was taken through a point in time recovery/flashback, resulting in a changed incarnation.

• The source database contains non-logged changes. In this case, a Resync is needed only if you are interested in moving the non-logged data over to the LiveSource.

• The LiveSource is significantly behind the source database due to network communication issues or a large number of writes.

LiveSource Resync is a two-step operation of:

• Start LiveSource Resync – Start Resync performs an incremental backup of the source database to transfer the latest changes to the Delphix Engine. This operation does not affect the availability of the LiveSource 

• Apply LiveSource Resync – Applying the Resync data will perform one more incremental backups from the source database to ensure up-to-date data, and recreate the LiveSource instance while preserving all the configurations. This operation requires downtime for the LiveSource.

• Discard LiveSource Resync – If the prepared resync data is no longer needed or resync has become obsolete (for example, another controlled change has been done on the source database), you can discard the current resync data with Discard LiveSource Resync. The next Resync will refetch data from the source database.

Pre-requisites: configuration and installation of staging environments to host a standby database

Oracle active data guard required

The LiveSource feature requires an Active Data Guard license. Delphix uses Active Data Guard to replicate changes from the source database that it creates on the staging environment.

Network requirements

LiveSource requires a Data Guard connection between the source and the standby database which utilizes TNS listeners associated with the databases.

Database requirements

LiveSource requires Enterprise Edition of Oracle Database.