Monday, November 4, 2013

Tape storage claims commanding capacity leadership

There is a torrent of computer storage announcements. Hardly a day goes by without some breaking news about new storage offerings. It is a veritable windstorm of information, and it is sometimes difficult to hear any particular voice in the maelstrom. Among the recent announcements was the interesting debut on September 12th by Oracle of the StorageTek T10000D tape drive and an 8.5 TB tape cartridge Oracle T10000D Announcement. Now, you may ask, what’s the big news with this announcement? The short answer is that this tape capacity is over 2X the capacity of the highest capacity Hard Disk Drive (HDD), 4 TB, which are used in enterprise disk and NAS systems today.   This has significant implications for overall storage infrastructure and cost requirements, especially for the storage of less frequently accessed data.

Let’s put this announcement in a bit of context. Imagine you had access to the Delorean featured in the movie “Back to the Future” and could travel ten years back in time to the year of 2003. For those of you that recall, the cry of “tape is dead” was echoing throughout the storage industry.  What tape cartridge capacities would you find? What HDD capacities would you find? You would find that the highest capacity cartridge was the 300 GB IBM 3592 Enterprise tape drive (OK, for those that are storage historians, there may have been other formats with higher capacities, but they were not widely used and were not commercial successes, I’ll confine my analysis to suppliers/formats that are still in the marketplace today). In the same year, the highest capacity HDD was 250 GB and it was being used in file server, block storage and specialized archive solutions.  The tape cartridge to high capacity disk ratio was 1.2X.

Given these capacities,the storage of 1 Petabyte (1,000,000 GB) of archive data would have required 3,334 of the highest capacity tape cartridges available. This many cartridges would have required a very large library (assuming that the data was not compressible).  If stored in a disk subsystem , it would have required 5,000 HDD’s , assuming that they were used in RAID 5 disk system (80% usable).  Needless to say, this would have required many disk systems that would include not only the enclosures for the HDD’s, but the associated control units.  

Contrast that with today’s technologies; with the 8.5 TB tape capacity, to store this same amount of data, would require only 118 of the StorageTek T10000D tape cartridges, which would fit comfortably in a small tape library or a small set of slots in a larger library. The disk system requirement has dropped significantly too, but still would require over 310 HDD’s and a couple racks of disk enclosures and control units.

The next couple of years will likely see increases in both HDD and tape storage capacities, but barring a radical change in direction, tape will continue provide historically high ratios of tape cartridge to disk capacities.  The bottom line is tape remains, and is likely to remain,  a very compelling and cost effective solution for the storage of less active data.