Trade group says study shows advantages of tape storage

Despite price improvements of disk-based systems, tape libraries remain the most cost-effective method of long-term storage, according to a study completed by the Tape Technology Council.

The council found that the cost for maintaining a terabyte-sized dataset on a tape library over three years runs about $102,000. In contrast, it would cost $150,000 to store that data on an optical disk jukebox and $416,000 on a mirrored RAID disk system, the council concluded.

To conduct the study, the council solicited bids from integrators for each type of system. The initial configuration would hold 10T of data and would accumulate an addition 10G of data daily.

According to the council, the study pointed out how the costs of a storage system go beyond the sticker price of the hardware.

'Many storage system purchasers focus their attention on up-front costs such as hardware and media costs [and] arrive at a comparative cost-per-gigabyte,' said council president Rich Harada in a statement. 'Although this cost is a good starting point for any system comparison, it's certainly not the full picture. By examining other factors that can play a role in the long term, the true advantages of one system over another become clear.'

The tallied costs include hardware and software, maintenance, floor space requirements and power consumption.

Mike Marchi, a senior director of Network Appliance Inc. of Sunnyvale, Calif., disputed the Tape Council's findings. NetApp is marketing its NearStore line of disk-based storage systems as an alternative to tape, one the company claims can offer faster retrieval at a competitive cost.

Marchi said the ratio between the cost of the tape system and that of the disk system in the study seemed pretty steep. He estimated that the average cost of a disk system runs closer to 2 1/2 times the cost of a tape system, rather than the fourfold increase the study found.

'The challenge with tape libraries is that they range in price significantly, from low-end to high-end,' Marchi said. 'If you look at a lower-end library, tape might have a cost advantage. But if you are looking at very large libraries, the costs are about the same.'

Marchi also said disk-based systems utilize software that can make more efficient use of storage space. For instance, rather than backing up an entire file, a feature called incremental block backup only saves changes to a file that has already been backed-up.

'Using more advanced backup technology changes the amount of information that can be stored on disk, as opposed to tape,' Marchi said.

The Tape Technology Council is a non-profit trade association of tape vendors including IBM Corp., Hitachi Maxell Ltd., Imation Enterprises Corp., Quantum Corp., Sony Corp., Storage Technology Corp. and TDK Corp.

About the Author

Joab Jackson is the senior technology editor for Government Computer News.

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