6.3.10 Format Obsolescence and Technology Cycles  The inherent nature of data storage is of constant progress and development, which means inevitable change, and ongoing obsolescence. Realistic long-term management of content must accept and build upon the continuing evolution and upgrading of hardware and media. Although central infrastructure such as data cabling or storage libraries may remain in operation for ten or twenty years, individual tape drives and media have a finite life much shorter than this. All of the main data tape formats have development roadmaps projecting upgrades every 18 months to 2 years. Backward compatibility for read-only access is sometimes assured over one or two generations of media within any common family. As a result,each generation of tape drives and media may be viable for 4 to 6 years, after which time it is essential to migrate the data and move on.1  Also the hardware maintenance cost of mass storage systems tend to rise notably when the system gets older than its projected life or the guarantee period ends. After this it may be difficult to obtain new spare parts for the tape libraries or tape drives, for example. A summary of projected roadmaps is presented below. Many formats have read-only compatibility with at least one previous generation.

Family 1st Generation 2nd Generation 3rd Generation 4th Generation 5th Generation 6th Generation
Quantum SDLT SDLT220 110GBytes SDLT320 160GBytes SDLT600 300GBytes DLT-S4 800GBytes    
IBM     3592 2004 300GB 40MB/s TS1120 2006 700GB 104MB/s    
Sun - Storagetek   9940B 2002 200GB 30MB/s T10000 2006 500GB 120MB/s T10000B-2008 ITB 120MB/s    
LTO LTO-1 2001 100GB 20MB/s LTO-2 2003 200GB 40MB/s LTO-3 2004 400GB 80MB/s LTO-4 2007 800GB 120MB/s LTO-5 no date (2009+) 1.6TB 180MB/s (estimated) LTO-6 no date (2011+) 3.2TB 270MB/s (estimated)
Sony S-AIT S-AIT 2003 500 GB 30MB/s S-AIT2 2006 800 GB 45MB/s        
Sony AIT     AIT-3 2003 100 GB 12MB/s AIT-4 2005 200 GB 24MB/s    

Table 1 Section 6.3: Projected Development Roadmap for Data Tapes

1. This implies a degree of waste and environmental pressure beyond the scope of our purely technological discussion, but in reality, a large-scale library of older data tapes will consume more polymers and require more petrochemicals for manufacture than a newer, high-density system with more energy-efficient drives and robotics, occupying less real-estate at the same time