6.3.13 Costs  Typically, the cost of data tape storage is spread in four areas: Tape media: procurement and replacement of primary and backup tape media every 3-5 years. Tape drives: procurement and replacement every 1-5 years, with support. Robotic Library purchase and maintenance within a 10 year life-cycle, and software purchase, integration/development and maintenance.  In a manual system, the costs for shelving will be lower, although the space requirement for staff is greater, and the labour cost for manual retrieval and checking is higher. In an automated robotic system, much of the human cost is offset by up-front expense for hardware and software. Large scale robotic tape libraries can be purchased in a modular fashion to spread the cost over several years as demand for storage grows.Within the life of a robotic tape library, individual components such as tape drives will be replaced by newer technology every three to five years. If content from an archive is accessed continuously the life time of drives can be considerably short, even only one year or less. Older tape media and drives may be kept on hand for redundancy if required. If an archive does not grow rapidly, the present and next generation of tapes and drives can co-exist in a tape library while the archive content is migrated to the next generation of media or technology. If an archive grows continuously it may be cost-effective to create a tape library of a specific size to only store the amount of content that shall be archived during the life time of the then current technology, and to then acquire a new larger tape library to store the content that shall be stored using the next generation of technology including the old content that will be migrated. The later approach is also necessary if old and new technology cannot co-exist in the same unit.  It is good business practice to keep at least one redundant copy of data off-site or geographically separate. Typically a radius of 20 to 50 km is common for natural and man-made disasters, and still allows manual retrieval within a few hours. To reduce risks further, redundant copies should be on different batches or sources of media, or even on different technologies. Some data tapes are only manufactured at a single supplier, and chances of a single point of failure are increased. Three copies of data are safer than two, and although costs for media increase, the hardware and software costs are only slightly higher than for the first copy.