Double Take FAQ Page 2

Yes. If the primary server fails, users can easily login to the secondary server and continue operations with minimal downtime and data loss. In fact, Double-Take can either automatically or manually have users redirected to the target server the instance the production server fails. Users do not need to make any changes and are likely to not even know there was a failure.

Yes. The failover module runs on the target server and continuously monitors the source servers. Whenever a source server fails, the failover module tells the target server to pick up the failed server's name, shares and IP address. It can also run a failover script, allowing you to automatically restart key applications on the target server.

Yes. Double-Take requires that a small and inconspicuous set of files be installed on each server acting as a source or a target.

No. Windows 2000 and Server 2003 include technologies that can be confused with Double-Take.

Intellimirror - Given the name "mirror", some people assume it is doing data replication. Intellimirror actually is designed to provide "roaming profile" functionality to Windows 2000 clients so their individual preferences are "mirrored" wherever they log in.

File Replication Services (FRS) - File Replication services is similar to the "Directory Replicator" included in Windows NT 4.0. Unlike Double-Take, FRS copies entire files every time there is any change (instead of replicating only byte-level changes) and performs periodic copying of closed files. FRS cannot replicate files that are open like Double-Take. FRS requires active directory to operate.

Microsoft Cluster Service - Since it can provide application failover, MSCS is often compared to Double-Take but they really solve different problems and in different ways. For more information on MSCS and its strengths and limitations (and ways to solve them), visit the Double-Take web site for information on GeoCluster.

Volume Shadow Copy Service (VSS) - VSS is part of Windows Server 2003 and Windows Storage Server 2003 and provides a way to create local snapshots, or point-in-time copies, of directories and volumes. These are not real time, but rather scheduled, and allow users to recover files from some time in the past. If the drive or server fails, all snapshots are lost. VSS snapshots cannot be used to rebuild a failed drive. Double-Take and VSS actually provide very powerful solutions when used in conjunction with each other. For more information on these solutions, please see the Double-Take and VSS whitepaper on the Double-Take Software web site.

Double-Take for Windows 4.4.

While compression of transmitted data can have a very positive impact on the data protection solution, it is not always optimal to utilize it, for a few different reasons. Compression requires additional processing which results in higher CPU usage. While some servers and applications can allow for this, there may be some where this is not acceptable. For this reason, Double-Take chose to allow its customers to determine when and where compression is suitable for their business and their data. Double-Take not only allows users to configure compression for on or off, but also allows users to set compression to one of three different levels, depending on the particular data being replicated. As the leader in enterprise data protection solutions, Double-Take Software provides the flexibility to meet the varying needs of its customers by allowing them to choose the level that is right for them.

Double-Take provides numerous methods of notification for events occurring in the replication and data protection environment. Events and messages can be viewed via the Windows Event Viewer as standard Windows events; can be viewed via a framework or other SNMP-compatible source via our SNMP traps, or via standard email, which could include pagers and cell phones enabled for SMTP. Separate notification methods and recipients can be configured on each dataset being replicated within Double-Take providing for different service levels for each dataset.

such as Microsoft Operations Manager?
Yes. Double-Take offers a Double-Take Management pack for Microsoft Operations Manager, which allows you to monitor all issues on all Double-Take servers across your enterprise. In addition, Double-Take can provide status and reporting information to other management frameworks like Tivoli, HP Openview and CA Unicenter through its integration with SNMP, Event Log Reporting and Performance Monitor counters.

You can download the Double-Take Management pack for Microsoft Operations Manager from the Double-Take Software Technical Support website.

While Double-Take does not prevent administrators from viewing or managing certain servers, it does allow individual administrators to create custom views of just a particular set of servers. Instead of searching through tens or hundreds of servers in the Double-Take management console looking for a particular one or few, administrators can create a view that will display just the server(s) that they are concerned with. Scalability is not an issue with Double-Take as hundreds of servers can be viewed in smaller subsets for separation of tasks between administrators and for ease of management.

The Replication product is a full-functioning Double-Take data protection product - with the exception of failover capabilities. All other Double-Take features such as in-band control, bandwidth throttling, data verification, advanced-scripting tools, etc. are still included. The Replication product will not allow failover from or to itself; this restricts it from being a failover target or a failover source. Replication SSE solutions are well suited for solutions like "Data Distribution", "Data Migration", and "Centralized Backup" of remote offices.

Yes, the SSE products are compatible and can coexist with any other product in the Double-Take line. They can all be managed via the same interface as well as replicate to/from each other. The only exception is the inability to fail-over to/from a machine running the Replication SSE product.

Yes, Double-Take provides 64-bit versions that run on Windows Server x64 Edition (AMD64 and EM64T) or Windows Server 2003 for Itanium-based systems.

Yes.

For extended 64-bit AMD64 and EM64T hardware and Windows Server x64 edition, you do not have to buy a separate license. However, for Itanium-based systems running Windows Server, you must purchase Double-Take for Windows Itanium 64-bit Edition.

Yes, Double-Take integrates tightly with the Microsoft Volume Shadow Copy Service to provide point-in-time snapshots of target data. These copies of the data can be used for recovery from human error, viruses or other data corruption.

Double-Take can take snapshots of the target in three ways:
Manually - you can take a snapshot anytime
Scheduled - you can schedule a snapshot at any interval, but Double-Take will not take a snapshot when the target data is in unknown state.
Automatic - Double-Take automatically takes snapshots before target data goes into an unknown state

You can store up to 64 snapshots. Older snapshots are automatically "pruned" to remove the oldest copy of the target data when a new snapshot is taken if the number of snapshots is at its maximum.

You can store up to 64 snapshots. Older snapshots are automatically "pruned" to remove the oldest copy of the target data when a new snapshot is taken if the number of snapshots is at its maximum.

You must be running Windows 2003 Server Service Pack 1 on the target Double-Take server. You can run any version of Windows Server supported by Double-Take on the source server.

You can utilize snapshots taken on the target by using the Microsoft Previous Versions Client, at failover using Double-Take or by manually mounting snapshots on the target server.