This article addresses the Neverfail Continuity Engine Data Rollback module which provides a method of recovering from data corruption.
At the completion of this session you should be able to:
- Recall the purpose of data rollback.
- Identify what happens to users applications during a rollback.
- Identify data roll back features and characteristics.
- Identify how to use shadow copies.
The success of a Neverfail Continuity Engine Failover or Switchover depends upon the integrity of replicated application data. Because data is vulnerable to many sources of corruption, including virus infection and user error, Continuity Engine may replicate bad data to the passive server if and when such corruption occurs.
To overcome this, Continuity Engine Data Rollback Module adds the ability to restore data and the configuration settings of protected applications to earlier points-in-time, before the data corruption occurred.
During normal operations, users remain connected to the protected application as the system continually captures and stores snapshots (which are used for data roll back operations). During a rollback operation, Continuity Engine temporarily disconnects users from the application as it replaces the data. Then Continuity Engine reconnects users after the rollback operation is complete.
Volume Shadow Copy Service
The Data Rollback Module uses Microsoft Volume Shadow Copy Service (VSS) technology to capture and store snapshots or shadows of application and registry data. A shadow copy is a frozen state of application and registry data at the time the snapshot was taken.
Data rollback has these characteristics:
- It captures only differences in data, reducing data storage requirements.
- It's store shadow copies at the disk volume level as read-only data.
- You can not use a shadow copy for any purpose other than as a source for restoring data.
Other design features include the following:
- Continuity Engine captures automatic shadow copies on the passive server.
- Continuity Engine capture shadows on the passive to avoid potential interference with the active server.
- You can configure Data Rollback to capture shadow copy daily on the active server.
- You can manually initiate a shadow copy at any time on any server.
This article discussed details of the Data Rollback Module. Remember these key points:
- The Neverfail Continuity Engine Data Rollback Module adds the capability to restore data and configuration settings of the protected applications to earlier point in time, before the corruption occurred.
- During a rollback operation, Continuity Engine temporarily disconnects users from the application while replacing the data.
- You cannot use a shadow copy for any purpose other than as a source for restoring data.