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Spectra Logic Backup and Archive Blog

 

Can Consumer Technologies Meet the Demands of Commercial Data Storage Applications

Over the years we have seen a variety of consumer technologies be deployed for commercial data storage applications. This approach was illustrated most recently at the Open Compute Project Summit with Facebook's prototype display of a Blu-ray optical disc library, which contains approximately 10,000 optical discs in a rack-sized cabinet. This is an interesting approach and one that I'll take a look at from a couple of angles in my next few blogs.

Using current 50TB per disc technologies, a system like this would hold 500TB or half a Petabyte. If Facebook used 100GB write-once discs, the solution could deliver a Petabyte of uncompressed storage per rack, with minimal power consumption. Excluding the cost of the robot and drives, the raw media costs of using 100GB Blu-ray discs works out to be about $0.41 per gigabyte and about $0.046 per gigabyte using 50GB discs. The cost of the Blu-ray disc system using either the 100GB or the 50GB disc is multiples higher than that of an LTO tape storage system, which costs a mere $0.02 per gigabyte.

Equally important, while a Blu-ray disc solution may meet the needs of storing Facebook consumer pictures and video, the real question is—will an approach that relies on consumer technology hold up to the long term demands of high-duty cycle data storage applications?

Over the last 20 years the commercial data storage industry has attempted to commercialize multiple consumer technologies including CD ROM, CD Writeable, DVD writeable, 4mm Digital Audio Tape, 8mm video tape, and VHS video tape—with mixed results. Consumer technologies offer high-volume and typically low cost storage media. The 'low cost' strengths of these technologies have also led to their downfall as they lack the device robustness and data reliability required by commercial data storage applications. In addition, consumer grade drives and media just don't last very long. Blu-ray disc drive load mechanisms are probably good to a few thousand load/unload cycles. This compares with an LTO tape drive that is rated to 250,000 load/unload cycles. As you can see—the difference in durability is substantial!

Facebook touted the space and energy efficiency of its Blu-ray prototype system as compared with standard commercial-grade disk storage, which is often expensive and, unless it can be powered down in "MAID" applications, consumes much more power. While true, this comparison overlooks tape storage solutions, which deliver the most reliable, scalable and cost-effective long term storage in the market.

At Spectra Logic, we've consistently invested in storage technology innovation that ensures we provide our customers with the lowest cost and most reliable storage for long term data retention. Our Enterprise T-Finity and T950 and mid-range T-Series tape libraries deliver features such as integrated data encryption, data integrity verification, media health monitoring, and extremely low power consumption, and are proven to meet the requirements of the most demanding data storage applications.

Tape storage has a proven track record of going the distance in serving commercial data storage environments. And, as I touched on here, tape offers the lowest price points available on the market for storing data for the long-haul.

Stay tuned! I'll provide a comprehensive cost comparison of tape storage versus Blu-ray disc in my next blog.

Comments (Comment Moderation is enabled. Your comment will not appear until approved.)
S Leyne's Gravatar While you are correct that on a storage density and transfer speed basis tape storage is better than BD/DVDs, you fail to consider file access speed in the overall solution.

It takes much less time to access a file on a BD/DVD then to access the same file on a tape -- assuming that the file is at the farthest distance to the read head.

By using BD/DVDs, Facebook is able to retain a high degree of random read functionality, which a tape solution does not.
# Posted By S Leyne | 2/13/14 4:15 PM
Bruce Kornfeld's Gravatar You are correct that optical (BD/DVD) has an advantage in time to data – however, I would suggest it’s not as big an advantage as some people might think. In Facebook’s archive architecture, the robotics to retrieve the disc would have to go through almost the same motions as a tape library robot:

1)   Move to slot
2)   Pick cartridge
3)   Move to drive
4)   Remove individual disc/tape
5)   Put disc/tape into drive
6)   Drive loads
7)   Drive seeks to first data block
So, the time that it takes to get the optical disc or tape to the drive (steps #1-6) may be about the same for optical and tape, assuming Facebook can achieve Spectra’s robotics speeds. (We’ve been building robots for a very long time and believe that the speed and reliability of our products are advantaged. However, for sake of argument we’ll assume Facebook achieves similar results.) The real advantage for optical is in step #7, where the load and seek time to first data block for optical will certainly be less than tape.

Tape drive technologies have advanced greatly in the past few years, and I think most people would be pleasantly surprised that a tape drive can access cold storage/archived data in about a minute (on average). While the load time of Blu-ray drives varies (and it's hard to confirm exact figures), it’s safe to say that it’s in the neighborhood of 35-55 seconds less than tape.

At the end of the day, in environments looking to reliably store cold data for long periods of time (years to decades), we think the vast majority of use cases will be OK with the cold storage data retrieval time of tape given the significant cost savings they can achieve with a tape storage system that is 95% less expensive than optical Blu-ray discs and consumes about half the amount of floor space in the data center.
# Posted By Bruce Kornfeld | 2/18/14 12:02 PM