There is no question about it -- the Digital Data Storage (DDS) tape and drive format has been -- and still is...
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-- an enormous success. It has been an ideal storage format for direct-attached applications like backing up PCs, workstations, and servers. In these settings, the capacity matches the need, the durability and reliability are high, and the cost is low. It's no surprise that even today, millions of DDS tapes are sold each year.
In fact, if PC hard drives didn't get bigger, and e-mail didn't allow attachments, and computers didn't get attached to LANs, and application software didn't add new features -- then there would be no reason to ever give up our DDS systems.
But the fact is hard drives are getting bigger, and e-mails now routinely include rich content, and LANs are even entering our homes. In my opinion the DDS format, as wonderful as it is, cannot keep pace with the growth of information to be stored. Manufacturers will continue to serve DDS users with tape for years, but for the users that need more space now, what's the next step?
According to a 2001 report from Gartner Dataquest, the estimated installed base for DDS tape drives in 2000 was more than six million. Some of these users are, right now, being driven to upgrade their storage systems. Others haven't felt it yet, but will within the next several years. This push is coming from at least one of the following: the need for more capacity, the need for faster transfer rates, and the need to increase the level of automation. In many cases, centralizing information storage or the growth of a function or firm may trigger all three factors. Adding DDS drives can, for a while, increase effective transfer rates, or add capacity, but at some point, it becomes evident that a line has been crossed -- a new class of storage is needed.
So we come to a new question: How to choose? There are many data storage formats with more capacity than DDS, surely one of these would be a good choice. But what other factors should users consider?
The truth is, nearly every application has a unique combination of requirements that makes one choice of current data storage formats the best -- for that application. There really is no such thing as "the best format" any more than there can be "the best tool." Whether you need a hammer or a screwdriver is a question of what you need to do -- not a question of which tool is inherently best. Each storage format is the result of engineering decisions that traded certain benefits for certain drawbacks.
So, while its difficult to say which format is best for your particular application, here is a "short list" of factors that is likely to be important to you when you make your choice:
1. Total storage capacity, both current and expected over the next several years
2. For backup, the available backup window, which dictates the required data transfer rate
3. The available space -- not only for the storage system itself, but also for the backup tapes, taking the retention requirements into account (Note that over time, it is quite common for the bulk of the required space to be driven by the recorded tapes – not the storage system.) 4. The storage budget -- and is the change intended as an investment in new capabilities, or as an operating efficiency enhancement (cost savings)
5. Retrieval: For backup purposes, it is common to think that the information will hopefully never be needed. But in the case of loss, the speed of recovery may be very important. In other cases, the information may be accessed repeatedly, and randomly; for example, account records.
For many current DDS users, migrating to an AIT format system may be an interesting option. AIT is now in its third generation with AIT-3, which holds 100 gigabytes (GB) native on each compact 8mm cartridge. At least three more generations are on the road map for release in the coming years; AIT-6 will hold at least 800GB native.
In part two of this series we examine how AIT systems stack up with respect to the key factors listed in the numbered checklist above.
Michael Nixon is a senior manager in the Storage Solutions Business Group of Sony Electronics' IT Products Division.