Server Mirroring
For Windows Servers

Mirroring with Double-Take

Mirroring is the process of transmitting user-specified data from the source server to the target server so that an identical copy of data exists on the target. When DoubleTake initially performs mirroring, it copies all of the selected data including file attributes and permissions.
Mirroring creates a foundation upon which Double-Take can efficiently update the target machine by replicating only file changes. If subsequent mirroring operations are necessary, Double-Take can mirror specific files or blocks of changed data within files. By mirroring only files that have changed, network administrators can expedite the mirroring of data on the source and target machines.

Double-Take’s flexible mirroring options allow you to choose which files are mirrored from the source to the target.

You can download an evaluation copy from here : Download Page

Replication

Replication is the real-time transmission of file changes. Unlike other related technologies, which are based on a disk driver or a specific application, Double-Take’s replication process operates at the file system level and is able to track file changes independently from the file’s related application. In terms of network resources and time, replicating changes is a more efficient method of maintaining a real-time copy of data than copying an entire file that has changed.

After a source and target have been connected via Double-Take, file system changes from the user-defined mission-critical data are tracked. Double-Take immediately transmits these file changes to the target machine. This real-time replication keeps the data on the target machine up-to-date with the source machine and provides high availability and disaster recovery with minimal data loss.

Failure monitoring/failover

Failover is a process in which a target machine stands in for a failed source machine. As a result, user and application requests that are directed to the failed source machine are routed to the target machine.

Double-Take monitors the status of machines by tracking network requests and responses exchanged between source and target machines. When a monitored machine misses a user-defined number of requests, Double-Take assumes that the machine has failed. Failover then occurs automatically, or, if configured, Double-Take prompts the network administrator to initiate failover.

The failover target assumes the network identity of the failed source. When the target assumes the identity of the source, user and application requests destined for the source machine or its IP address(es) are routed to the target.

After failover, user and application requests directed to the source machine are routed to the target machine.

When partnered with Double-Take’s data replication capabilities, failover routes user and application requests with minimal disruption and little or no data loss. In some cases, failover may be used without data replication to ensure high availability on a machine that only provides processing services, such as a web server.

Restoration

Restoration provides an easy method for copying replicated data from the target back to its original location on the source. The process only requires you to select the source, target, and the appropriate replication set. There is no need to select files or to remember where the data came from on the source since that information is maintained by Double-Take.

Restoration can be used if the source data is lost due to a disk crash or when the most up-to-date data exists on the target due to failover. At the time of a source machine failure, your Double-Take target will contain the same data as your Double-Take source. If you are using Double-Take’s failover capabilities, users can continue updating data on the target machine while the problems on the source are resolved. Because of the continued updates on the target, when the source machine is ready to come back online, the two machines will no longer contain the same data. Restoration is the process of copying the up-to-date data from the target back to the original source or new source location when bringing the source back online.

Double-Take’s flexible restoration options allow you to choose which files are restored from the target to the source.

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