WAN Backups - Innovation for an Oldfangled Technology - Page 2

 By Beth Cohen
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How WAN Backup Works

WAN backup software and systems take one of two basic approaches to solving backup problems. Either they copy your staff’s key data files to a centralized backup server (your company’s server or a service provider’s system) only when the systems are actually network connected, or alternatively, they continuously replicate file system information between distributed systems. Both methods are effective, but each has slightly different requirements and implications.

A network server backup is commonly implemented with a mobile work force that might only be connected an hour or so a day. Normally the user will be prompted to perform a backup before they logoff. The advantage with this method is that it’s very flexible about the number of systems that can be supported. However, the disadvantage is that the user might either rarely connect or skip the backup due to the time it takes, leaving them and the company vulnerable to unexpected and unacceptable data loss.

The other network backup system only copies the pieces of the files or bits that are different. Think of it as applying old database replication notions to a standard file system. These backup applications solve the old database problem of backing up always-open files.

The same methodology used to minimize bandwidth in streaming videos, video conferencing, and large database systems is applied to backup technology. As Ohlenbusch puts it, “By using byte-level differencing technology, Availl's flexible mirroring technology instantly replicates files (one way or bi-directionally) in real-time, to or between any numbers of systems."

Because Availl 2.6 only transports the differences between the files, not the entire files, it minimizes the network load of the replication process. Perfect for files that change constantly, large numbers of files, extremely large files, application files (web servers, databases, etc), data for remote offices, disaster recovery needs, CAD files, or data that needs to span any number of servers located anywhere, the byte-level differencing technology transparently results in 95% bandwidth reduction, with files always continuing to be useable.

Outsourced Backup Service or In-House System?

So, which type of approach will work best for your business? The choice is dependent on the specific needs of your company. If you have many mobile users who are only dialing up or accessing the network an hour or so a day to check their email, but who are not performing much synchronous file sharing, you are probably better off with an Internet-based backup service or a centralized backup server.

The outsourced service cost is normally based on a monthly charge per system, and it offers the maximum flexibility as your backup needs change. If the economics work for you because you already have substantial investment in a data center and staff, you have the option of installing and maintaining such a system in-house as well.

If you have a number of fixed remote offices with local servers, then using a distributed product like Availl’s is a logical solution. With the added complexity of users commonly sharing complex data files and a need for integral disaster recovery, a distributed WAN backup system has many advantages. Of course, you will need to install and maintain it in-house, as this service is not currently available as an outsourced option.


If you have multiple remote sites or users and you are sharing distributed data, you owe it to yourself to be looking at this technology. Whether you decide to host a remote solution in-house or use a remote backup service provider, you should seriously consider distributed data mirroring and storage software that allows you to back up your systems and synchronize your files across multiple locations. The bottom line is that unless you have a real need to hold on to those stackers and you love the smell of backup tapes, it might be time to retire them and move up to the next generation of backup technology.

Additional Resources

www.availl.com – Availl Inc. Website
remote-backup.com – Vender of remote backup software to service providers
http://www.snia.org/tech_activities/workgroups/backup – Storage Networking Industry Association's Backup Workgroup

Beth Cohen is president of Luth Computer Specialists, Inc., a consulting practice specializing in IT infrastructure for smaller companies. She has been in the trenches supporting company IT infrastructure for over 20 years in a number of different fields including architecture, construction, engineering, software, telecommunications, and research. She is currently consulting, teaching college IT courses, and writing books about IT for the small enterprise and wireless network security.

» See All Articles by Columnist Beth Cohen

This article was originally published on Nov 17, 2003
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