Data back-up software overview
Back-ups are typically performed during off hours with few personnel available, so back-up software often emphasises the use of automation. This typically includes keeping track of back-up schedules, managing the timely transfer of data volumes to target tape or disc locations, handling compression and data deduplication to reduce media use and speed the back-up process, and can even include encryption to secure back-up data against loss or theft. Some back-up software emphasises "business intelligence," supporting back-up reporting and analysis to help IT departments optimise their back-up operations. Alerting features generate pages and e-mails to keep IT personnel informed of back-up status, and can even call for assistance if problems arise.

Lan-free and server-free back-ups

Traditional back-ups stage data onto a server and then push the data out to a tape drive, tape library, virtual tape library, or other storage target. But this is an inefficient approach because the back-up server is only utilised during the back-up process, and tremendous network bandwidth is needed to transfer back-up data to the target, so the Lan is almost unusable during the back-up. This approach is changing by systematically moving back-ups off the Lan and onto the San, so you should understand the difference between Lan-free and server-free back-ups.

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Lan-free back-ups avoid utilising the user network by employing the San directly. Data is taken directly from a San disc, handled through an application server on the San and then passed directly to another San storage device. The Fibre Channel San infrastructure allows for high back-up speeds up to 100MBps. Only metadata about the back-up data will pass across the Lan, so the impact on Lan bandwidth is minimal. Server-free back-ups also avoid Lan use, but further streamline the Lan-free process by reducing the back-up work performed by the application server -- ideally moving data directly between San locations. While the resulting back-up throughput still tops out at about 100 MBps, it uses the Extended Copy command set (a set of SCSI commands not yet approved by the American National Standards Institute T10 committee) to minimise the CPU, Ram and I/O overhead on the application server.

Performance monitoring and reporting

Monitoring is an important part of the back-up process -- it helps administrators understand how efficiently the back-ups are being executed in their particular environment. By quantifying the elements of back-up performance, improvements can be implemented to optimise or streamline the process. As one example, performance monitoring might reveal better back-up throughput between 2:00 a.m. and 5:00 a.m. due to lowest network utilisation. This in turn might justify a shift in the back-up window. Similarly, low-throughput from the back-up server to the tape library may explain why excess "shoe shining" is inflating back-up windows and reducing tape life. Performance results can highlight the need for network infrastructure upgrades or media changes.

Back-up software should also provide comprehensive and configurable reporting features. High-level reports help management to follow overall back-up statistics on a weekly or monthly basis, while low-level reporting can identify possible back-up bottlenecks or media with frequent problems. Alerting is another vital feature of back-up software, allowing notable events or status updates to be forwarded to corresponding IT staff. For example, an alert can indicate that a back-up process failed to run properly, and immediate attention is required. Monitoring and reporting is sometimes implemented as standalone products that are separate from back-up software. Back-up Advisor from EMC is one such standalone product.

back-up testing

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The IT perspective on back-up is changing. Rather than performing back-ups simply for the sake of copying data, storage administrators are increasingly addressing back-ups from the standpoint of recoverability -- backed up data is useless unless it can actually be recovered. This makes back-up verification and testing features more important, and any back-up software should include features that simplify back-up testing.

Beyond verification, organisations must practice their recovery on a regular basis. In many cases, organisations perform recovery drills by deleting unneeded "test" files that are maintained on the server, and then using the back-up software to recover those files.

General purchase considerations

Back-up software must be selected for its feature set and suitability for your own particular environment. However, there are some common issues to consider:

Ease-of-use. Tools that are cumbersome or overly complicated will not be used to their best potential. An IT staff should have the opportunity to test several prospective tools in a lab environment, providing comment on the feature set and user interface. Advanced features may require a modicum of training but should demand little, if any, formal training for basic features.

Compatibility. It's important for software to support the current -- and possible future -- hardware in your environment. Homogeneous environments may not be such an issue, but heterogeneous environments with a variety of hardware may prove more problematic. Network Data Management Protocol (NDMP) offers an open protocol that supports back-up tasks in heterogeneous network environments.

Specialised features. Back-up software will typically transfer files to tape or disc storage. However, an increasing number of software tools support data protection features like archival back-ups (e.g., content-addressed storage), continuous data protection, snapshots, mirroring or replication. Select back-up software that complements your back-up emphasis. For example, a tool like EMC's RecoverPoint allows for frequent snapshots to disc, while Symantec's Netback-up offers general purpose tape/disc back-up and restoration.

Application integration. If your goal is to support specific enterprise applications, consider the level of integration that the back-up software provides for those applications. For example, EMC NetWorker software supports modules integrated with vendor-specific application programming interfaces eliminating custom script development for applications like IBM Lotus Notes/Domino, Microsoft Exchange or Sybase.


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This was first published in September 2007

 

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