Study quantifies archive cost of ownership

Recurring annual operating costs related to powering and cooling magnetic disk archive storage systems amount to a major expense, according to a new archive ownership study.

The study, presented at the SCAR meeting Saturday, analyzed the most significant financial factors in a long-term record archive using common archival storage technologies: magnetic tape, magnetic disk, and three optical storage technologies - DVD, ultradensity optical (UDO), and magneto-optical (MO).

"Archive storage costs have been frequently discussed, but the total cost of ownership has seldom been properly quantified," said Andrew Richards, vice president of business development of Plasmon.

The most surprising finding was related to power and cooling costs associated with magnetic disk systems, Richards said.

"The annual maintenance and operating costs for cooling and powering of magnetic disks is dramatically greater than for tape or optical systems," he said.

When adjusted for cost of ownership over three years, operating costs of magnetic disks can easily approach $10,000 per year, Richards said. Powering and cooling costs associated with tape and UDO systems were negligible.

Magnetic disks made up some financial ground in cost of floor space, claiming only 0.9% of total footprint cost. The other options all occupy larger spaces: DVD, 5.05%; UDO, 4.56%; MO, 4.39%; and tape, 3.27%.

Richards cited a scenario in which a facility required a 12-TB archive measured over three years of operation, based on daily archive volumes averaging 8 GB and factoring in yearly growth rates of 30% to 40%.

Among the costs included in the study were hardware and software acquisition, media acquisition, hardware and software maintenance, powering and cooling, and floor space.

"The results clearly show that the total cost of ownership of tape, DVD, and UDO archives are similar and are far lower when compared with MO and magnetic disk," he said.

The study found that over half the cost of tape and optical systems was for hardware (tape 53%, UDO 54%). The primary cost component of the magnetic disk system was found to be software-related (42%).

"That was another surprise, that software was over a 40% component in disk costs," Richards said.

As expected, tape had the lowest media cost (5.1%), and DVD (24.2%) and MO (24.2%) the highest.

The study found the cost per GB for each technology: $10.79 for tape, $11.01 for DVD, $12.80 for UDO, $36.31 for MO, and $41.48 to $62.96 for magnetic disk, depending on whether the systems were mirrored.