computing lives - FTP Directory Listing
computing lives - FTP Directory Listing
computing lives - FTP Directory Listing
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Computer Previous Page | Contents | Zoom in | Zoom out | Front Cover | Search Issue | Next Page M S BE<br />
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44<br />
COVER FEATURE<br />
Edward Walker, University of Texas at Austin<br />
Storage clouds are online services for<br />
leasing disk storage. A new modeling<br />
tool, formulated from empirical data<br />
spanning many years, lets organizations<br />
rationally evaluate the benefit of using<br />
storage clouds versus purchasing hard<br />
disk drives.<br />
Hard disk drives provide storage for a broad range<br />
of devices, from mobile phones to large IT<br />
server farms. In 2008, approximately 590 million<br />
hard disk drives were shipped worldwide, 1<br />
largely driven by the vast amount of information<br />
our digital society is generating. For example, a report<br />
from researchers at the University of California, Berkeley,<br />
estimates that 92 percent of the five exabytes (10 18 ) of<br />
new information created in 2002 was stored on magnetic<br />
media, primarily hard disk drives. 2<br />
At the same time, the business of selling infrastructure<br />
as a service through the Internet is growing. This technology<br />
trend, also known as cloud <strong>computing</strong>, lets individuals<br />
and organizations outsource their IT requirements to<br />
remote data centers, paying for only what they use. The<br />
cloud <strong>computing</strong> industry’s worth was estimated at more<br />
than $16 billion in 2008, and it’s expected to grow to $42<br />
billion by 2012. 3<br />
Several online services currently lease storage infrastructure.<br />
These storage clouds let anyone with a credit<br />
card purchase storage capacity online, paying a monthly<br />
fee for the storage they use. __________<br />
Amazon.com’s S3 service<br />
(http://aws.amazon.com/s3), for example, lets users store<br />
COMPUTER<br />
TO LEASE OR NOT<br />
TO LEASE FROM<br />
STORAGE CLOUDS<br />
Walter Brisken and Jonathan Romney, National Radio Astronomy Observatory<br />
arbitrary objects of up to 5 Gbytes each in their online<br />
storage repositories. The S3 service uses a tiered pricing<br />
structure, with storage getting cheaper as more is used. As<br />
of late 2008, Amazon.com reported that users stored more<br />
than 40 billion objects in the S3 service. 4<br />
With the significant growth of society’s storage requirements,<br />
and the availability of pay-per-use online storage<br />
services, when should a consumer consider using storage<br />
clouds? We focus on the problem of resolving this buy-orlease<br />
storage decision.<br />
BUY OR LEASE<br />
An organization’s decision to buy or lease long-term<br />
assets is often a critical dilemma. The literature describes<br />
numerous models to assist firms in resolving this acquisition<br />
decision. 5-7 However, there is a significant lack of work<br />
in applying these models to compare the cost of purchasing<br />
versus leasing storage from cloud services. Important<br />
studies have examined the cost of performing scientific<br />
experiments using the Amazon.com cloud services, 8,9 but<br />
these prior works are difficult to generalize outside the<br />
scope of the applications used in the studies.<br />
We believe our proposed model for evaluating the benefits<br />
of purchasing versus leasing storage from a cloud<br />
service is the first reported in the literature, offering a<br />
method for deriving a reasonable estimate of the best possible<br />
outcomes from the alternative investment choices.<br />
Furthermore, our model, which we formulated using<br />
empirical disk price data we’ve been collecting weekly<br />
from Pricewatch.com over many years, is agnostic to the<br />
application using the storage cloud. Our empirical data<br />
tracks the lowest prices for serial advanced technology<br />
attachment (SATA) disk drives for sale online since the<br />
Published by the IEEE Computer Society 0018-9162/10/$26.00 © 2010 IEEE<br />
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