Efficient network storage MARK LEWIS EMEA marketing director, Riverbed Technology


Centralising storage at the corporate data centre makes all the sense in the world, particularly for information that must be consistently available to employees at headquarters, in branch offices, and sometimes executives on the road. Replicating key data between multiple corporate data centres so that important information is never lost is also sensible. So is periodically transmitting live backups to an offsite disaster recovery facility.


Such continuous movement of large volumes of data across the network would have been impractical just a few years ago. Now, it’s practically a necessity.


For example, an effective disaster recover strategy requires that all data be stored redundantly at multiple physical locations. In the event of a disaster that destroys data stored at one location, there will always be a second, redundant copy of the lost data at a different physical location. Such a strategy ensures that a single cataclysmic event, such as hurricane, flood, or terrorist act, will never destroy all of the data that a corporation has.


Traditional techniques of running nightly backups to tapes or other physical media and then trucking those tapes off to a secure location are starting to look positively quaint. Data volumes have grown to the point where backups can’t necessarily be accomplished in a nightly backup window. In any case, many businesses can’t tolerate losing even a few hours of corporate data or risk the possibility of tapes being lost in transit. That makes live incremental backups throughout the day a much better alternative.


However, this transformation of how we manage data storage comes with its own complications. In particular, if not managed properly, highly distributed network storage can result in an excessive strain on wide area network (WAN) connections. That translates into poor performance for file transfer and replication protocols, as well as applications that depend on them. Meanwhile, a WAN circuit that is overloaded because a backup job is running may not provide the performance required for other applications to work properly.


With the advent of cloud storage services for backup and recovery, efficient use of network capacity becomes even more important because these services rely on the Internet, meaning


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they are even more subject to congestion and latency than applications on the corporate WAN.


The good news is that there are solutions to these challenges. WAN optimisation technology can squeeze more capacity out of whatever network bandwidth is available. Often, this technology is delivered in the form of an appliance – a network device preconfigured to run the software that will perform these optimisation tasks. In highly virtualised and cloud computing environments, it can also be delivered as a software-only virtual appliance that can be loaded into a virtual machine like any other application.


While these deployment options are largely a matter of preference, some of the more high-end appliances do have advantages like encryption co-processors for accelerating SSL encryption beyond what is possible with software alone. The basic techniques of WAN optimisation include


“In combination, these protocol and deduplication optimisations often allow a single file to be copied across


the WAN more than 250 times faster than would be possible to without optimisation. An entire directory of files can be copied nearly 20 times faster, while lowering the bandwidth required by up to 98%.


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compression, data de-duplication, and protocol specific optimisations.


Like many enterprise applications, network file systems like the Windows Common Internet File System (CIFS) grew up around local area networks (LANs). In other words, they were designed to transmit files around the building or across the campus, not


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