What are the benefits of using a virtual tape library (VTL) for data deduplication?

What are the benefits of using a virtual tape library (VTL) for data deduplication?

Well, there are a few big use cases right now that are driving data deduplication to the forefront of the decision-making that's going on in backup environments. The bottom line is data deduplication is dramatically changing the economics of using disk as a backup target as opposed to tape. You can only buy so much disk before you run out of funding, but there are a few other drivers. One is tape reduction -- that's the most obvious. Also, VTL deduplication provides an alternative to first-generation VTLs (in the 2003 to 2004 timeframe). And, the last is an encryption-avoidance strategy. Companies that are looking at media loss risk -- and are facing operational, litigation or reputation risk as a result -- have started to compare tape encryption, and how to do that with a tape reduction strategy that allows the company to use a deduplicating VTL and site-to-site replication. Other benefits include reducing the complexity of operations and requiring fewer hands-on at remote sites or even at core sites for tape management.

Another factor here is that there are various VTL interfaces. You have the classic VTL interface, in which the device, emulates a tape library using Fibre Channel (FC) connectivity. However, there are also devices that connect via CIFS or NFS. These are just different means for getting your data into a data deduplication device. At this point, it's less about the interface and more about your protocol and connectivity preferences. Do you want to use FC or do you want to use iSCSI? More and more, this is less about the actual functionality, and more about the performance and integration strategy that you want to take.

With the first-generation VTLs, that testing was limited, and a lot of customers really paid the price by learning about the technology in house and how it affected production environments. These customers really educated the vendors about how disk technology performed, scaled and integrated with the various backup products. Also, there were a lot of integrated or tape-staging-type of architectures where the VTL was writing off to tape. There were very few vendors out there at that time that really had a deduplication capability; there was Data Domain, Avamar and Permabit, and there were bottlenecks in all of the designs out there.

Data deduplication is generally available in almost all of the second generation of VTLs out today, and if they are not generally available, then they are in beta testing. All of the innovative vendors are making a hard push into data deduplication. Things are getting better and faster and the vendors are overcoming some of the engineering challenges. There's also a big move away from tape staging. Users are now using hybrid approaches -- using current disk and tape assets with data deduplication in their architecture.

Click here to check out the entire VTL Deduplication FAQ.


This was first published in September 2008