Cloudy with a 00% Chance of Tape

Public cloud storage represents an interesting dichotomy many users love its flexibility and manageability while others fear the security risks and loss of control. To be fair, the split opinions are often aligned with company size with smaller organizations more likely to endorse the former position and large ones the latter. However, one challenge that companies of all size face is cost it takes a different mindset to move from the traditional capital intensive storage procurement model to the operational cost model of the cloud. An offering from Amazon Glacier caught my eye as a solution that significantly reduces the price of Amazon's storage offerings.

Glacier is Amazon's inexpensive cloud storage offering and its economics are eye-opening. The solution provides storage that is between 5x and 9x less than Amazon's traditional cloud storage offerings while bringing similar benefits in terms of dynamic scalability and optimized manageability. (Note that there is an access time trade-off with Glacier which I will discuss later.) This is a significant discount and it makes me wonder how they created this solution and whether other providers will follow.

Tape appears to be the key enabler of Glacier. As pointed out in an article titled, Spectra: Tape is dead? We installed 550PB of the stuff in 6 months by Chris Mellor at The Register, Glacier is relying on tape libraries from Spectra Logic and is delivering the service via LTO tape technology. This is a dramatic change since most cloud providers rely exclusively on disk systems to store and retrieve data. When you think about it, this makes a great strategy. Tape is inexpensive on a $/GB basis, highly reliable and extremely scalable. In fact let's look at some key metrics for tape as compared to disk.

Cost: An LTO-6 tape will cost about $100 and can deliver up to 6.25TB in capacity. For $100 you can buy a 2TB desktop drive. Quality differences aside (Storage vendors will never sell you a $100 desktop drive due to their reduced duty cycle and reliability. They will use tested enterprise drives which cost hundreds of dollars more.), you are getting more than 3x the storage capacity with tape for the same price. Curtis Preston included a good cost analysis in his post, titled Get rid of tape? Inconceivable!, and he estimated that storing 20PB of data would cost $22,000 on tape or $12M in disk.

Reliability: LTO tape has a bit error rate that is 100x lower than that for enterprise SATA drives

Scalability: With a tape library adding capacity is simply a matter of purchasing more tape cartridges while additional performance can come from adding tape drives. Many disk subsystems are scalable, but it is rare to find one that can scale to such large capacities as tape-based solutions and can grow either capacity or performance.

Standards: LTO is a standard. Any tape drive can read any LTO tape (up to two versions of LTO backwards compatibility). The world of disk subsystems is a proprietary one. Disk shelves or disk drives from one vendor can rarely be used in another's system and so it is extremely difficult and costly to switch vendors.

These same metrics that make tape extremely compelling for Glacier also make the technology beneficial as a backup and archive target. To be fair, tape access times can be slower than disk speeds, but for many applications this is a worthwhile trade-off when considering the economic benefits. Now in the case of Glacier, tape appears to be the exclusive storage medium, but corporate IT customers can use tape as part of a broader information management strategy in combination with spinning disk to combine the access time benefits of disk and the compelling economics of tape. This hybrid approach leverages the best of both disk and tape technologies.

Amazon has done an admirable job in extending their cloud offering to tape by using Glacier. There is no doubt that other competitors will follow and so if I look at the trends in IT, our forecast is cloudy with a 100% chance of tape.

LINK:	http://blog.ironmountain.com/2013/data-backup-and-recovery/cloudy-with...
	See more stories from ironmountain

Most recent headlines