Two countervailing forces are driving much of IT purchasing these days. The first results from the happy circumstance that the cost of actual physical storage is diminishing. Disk drive technology has enabled a predictable curve that provides larger capacity disks that take up lessening amounts of space and cost fewer dollars to buy. Additionally, smaller disks require less power, which offers opportunities for cheaper cabinetry and lower running costs.
The new serial storage protocols, serial-attached SCSI (SAS) and serial ATA (SATA) have also led to much efficiency in cabinet design. In both cases for example, reducing the size of cables has meant that air flows more easily between the drives and the backplane. This in turn helps to reduce costs for cooling JBOD devices (disks that are put in arrays and typically connected directly to a backplane don't get this particular benefit but can take advantage of others).
When it comes to tape, technologies continue to improve and deliver better value. A look at the new set of Linear-Tape Open (LTO) products for instance shows that total storage and throughput also continues to improve significantly at each price point - roughly the same investment today provides much greater benefit in both categories than it did just two years ago.
The second driving force however is much less pleasant: the costs associated with administering, protecting, and maintaining storage are rising at an alarming rate.
It is tempting to assume that the better value we receive at the front end whenever we purchase such new products offsets the increased costs for managing all our new storage. Unfortunately, as any manager will tell you, this is never the case.
It is important to differentiate here between the purchase price of hardware and software - the capital expense (CAPEX) - and the ongoing costs of operating the IT environment (operational expenses, or OPEX).
The most significant difference between the two is also the most obvious one - a capital expense occurs just once, but you are stuck with the OPEX for the life of the product. Thus, if you expect to keep a piece of equipment around for five years, it will have five years of operational expense associated with it.