Overview - ContinuousDataReplicator

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Introduction

ContinuousDataReplicator (CDR) provides protection of application data and file systems, by replicating data from a source computer to a destination computer in nearly real-time. (See Replication Logs for specific information about frequency and timing of data replication.) CDR software simplifies the basic configuration, operations, and monitoring of data replication activities, employing wizards and policies for configuration tasks, a separate Data Replication Monitor in the CommCell Console that tracks all replication activities, and specific reporting and activity history tools for additional monitoring.

Application Awareness

For supported applications, CDR will assist in configuring Replication Pair content by discovering directories that should be replicated (logs, databases, etc.) to protect the application's data. After data for these applications has been replicated, you can browse and access the Live Copy of the data.

CDR Recovery Points

High availability of protected data in a consistent state is also available by creating Recovery Points, through the use of snapshots created on the destination machine. These Recovery Points can be mounted, shared as a volume on the network, or recovered using Copyback. After a Recovery Point has been created, the data can also be backed up, using the appropriate File System iDataAgent. This provides additional protection for your data, as well as additional options for recovery of your data. For more information, see Replication Scenarios.

Consistent Recovery Points, which define a point-in-time where application data is in a consistent state on the source computer (the application server) can be created using CDR, ensuring the application data can be restored to that point-in-time. Recovery Points can also be created directly from a snapshot of the replication volume on the destination computer, but this does not preserve application data in a consistent state, and thus is more useful for file system data. Recovery Points can be created, retained, backed up, mounted, and for Windows can also be shared, and thus made available to users on the network. This allows data to be protected, accessed, and recovered in a variety of ways. For more information, see Recovery Scenarios.

CDR in the Enterprise

CDR is just one of several Agents that provide data protection and recovery support for different kinds of data in what is often a heterogeneous network environment. The following figure shows an example of a simple CommCell configuration using CDR.

Supported Data Types

Data protection operations for the data types listed below are supported by ContinuousDataReplicator. Note that Windows data can only be replicated to another Windows computer and UNIX data can only be replicated to another UNIX computer.

Windows File Systems

  • When replicating a root volume (e.g., C:\), paging files, the System Volume folder, and the hibernation files will be filtered out automatically from Replication Pair content, and will not be replicated to the destination machine.
  • It is recommended that you use recovery points on the destination for examining consistency of data on a destination computer, as comparing live data on source and destination may result in the files not matching.
  • Also refer to Application Integration - Non-Integrated Applications.
  • For a complete listing of applications supported for each operating system, see ContinuousDataReplicator - Application Support.
  • For full details of the operating systems supported, see System Requirements - Continuous Data Replicator.

Unix File Systems

  • CDR on UNIX will not replicate such file system directories as /, /usr, /var, /tmp.
  • For CDR on Linux, we only support VERITAS File System (VxFS) on volumes created by Veritas Volume Manager.
  • During the Baselining phase, CDR on Unix will transfer sparse files as regular files; however, during the Replication phase, sparse files will be replicated as sparse files, and regions of the file that do not require disk space will be unallocated.
  • The memory mapped files are not supported for AIX and Solaris.
  • For a complete listing of applications supported for each operating system, see ContinuousDataReplicator - Application Support.
  • For full details of the operating systems supported, see System Requirements - Continuous Data Replicator.

Tree Levels in ContinuousDataReplicator

After ContinuousDataReplicator is installed, Replication Sets and Replication Pairs can be created in the CommCell Browser.

bowa: Client

ContinuousDataReplicator: Agent

Set1: Replication Set

 H:\data: I:\data33232: Replication Pair

Use of Snapshots with CDR

CDR utilizes snapshot technology for certain phases of its operation, both on a source computer as well as a destination. Different snapshots are available for different operating systems, and different operations as follows:

CDR on Windows:

QSnap

VSS

CDR on Linux

File System Snapshot

QSnap

CDR on AIX:

File System Snapshot

CDR on Solaris:

File System Snapshot

QSnap

If you are using the UFS or VxFS File System, then do the following:

Additional Snapshot Information

Use Cases

Following are some specific uses of CDR:

Change Journal

ContinuousDataReplicator on Windows, the Data Classification Enabler on Windows, and the Windows File System iDataAgent use Change Journal to track updates made to Windows File Systems. On very large or very busy file systems, it may be necessary to increase the size of the change journal in cases where the agent or enabler is performing full scans too frequently. You can control the amount of volume space that is allocated for Change Journal when it is created by using the dwCJSizeAsPercentOfVolumeSize registry key value.

License Requirement

To perform a data protection operation using this Agent a specific Product License must be available in the CommServe® Server.

Review general license requirements included in License Administration. Also, View All Licenses provides step-by-step instructions on how to view the license information.

A Feature License is required for Recovery Points, which allows snapshots to be created from the destination computer.

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