Originating Author: David Vellante
Contributing Author: Fred Moore
IBM presented a model today during its call to announce new tape products that stressed that tape is greener than disk by a wide margin and tape innovation continues, despite pressure from emerging disk technologies. The IBM model also showed tape costs are comparatively lower than disk. IBM analyzed a 250TB data requirement growing at 25% per annum and demonstrated that over ten years:
- A SATA disk configuration costs $6.4M (excluding labor costs)
- An LTO tape library costs under $1M (excluding labor)
- A blended disk/tape combination costs about $2.3M (excluding labor)
However, the innovations of of MAID, disks in a cartridge, removable disk/SATA hybrids and VTL are taking the TCO of disk closer to that of tape. While tape libraries currently enjoy a lower $/GB and OPEX than any type of disk, the predominant use of tape is in data centers and the upper-end of the SMB market. Tape has effectively been eliminated on the desktop, very low-end servers, low-end SMB applications, in the car or home. The total available market for tape appears to be shrinking as the reach of disk is expanding.
Nonetheless, the media life of new tape is now 15-30 years (versus 5-8 years a decade ago). SATA disks have a useful life of about five years before migration and conversion are needed. Tape is the better long-term archival media based on cost, media life and ease of portability. Notably, tape consumes orders of magnitude less power than disk.
While backup applications are moving to disk, archival, fixed content and compliance applications are still best economically suited for automated tape. Tape clearly is more than backup. The tape industry will need to answer the de-dup function with some other type of data reduction scheme and open systems VTL's will adopt de-duplication technologies in the near term.
So where does this all leave tape? The future of tape includes disk, that is a disk array that front-ends an automated tape library. In this instance, users get the performance of disk for more active data and the economics of tape for the larger amounts of archival data with data movement occuring directly from disk to tape without involving any server or appliance. This links tier 2 and tier 3 storage together where migration can, in theory, be automated.
Action Item: When it comes to tape decisions, consider applications before anything else. Long term T3 storage (archival, compliance and fixed content apps) will remain the domain of tape as the economics are more favorable. A blended disk / tape approach is emerging as a likely reference model for T2-->T3 storage migration and IT should prioritize bringing mainframe-like processes to manage the movement of data from online to nearline to offline.
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