What are the drawbacks of using a virtual tape library (VTL) for data deduplication? There are really no alternatives for disk-based backup outside of backup software options. For example, Symantec has PureDisk that offers a data deduplication function at the client. IBM is soon to release a similar function in its software product. Other products like Avamar or Asigra have a software capability. And while these have a lot of play in smaller production environments, they have limited reach into enterprise environments where scale and performance requirements are really high.
Another potential drawback is that, with the exception of a few of the vendors, the technology is less proven. In fact, some vendors have only had data deduplication in production for a matter of months. It's great that it works, but no one really has a long-term understanding of the risks associated with the technology. You'll hear a lot of arguments around hash collisions, for example, which are statistically based -- not based on actual data loss in production.
Also, if you look at what happened with the first generation of VTL products, most of the vendors approached this from a really simplistic point of view. They tell you that you can take their product and plug it into the backup environment and all your problems will go away. But, almost every customer I've dealt with has not had that experience. In many instances, the first-generation VTLs were pretty miserable because things didn't work because there were bottlenecks and backup software integration was not really considered as part of the picture.
So, when you look at the typical backup environment today, the fundamental design has been tweaked but not exactly overhauled since the initial deployment of VTLs. For many companies, a refresh of the design and technology is long overdue, and right now data deduplication is a really good catalyst to do this.
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