18-04-2014, 04:25 PM
Impact of Storage Acquisition Intervals on the Cost-Efficiency of the Private vs. Public Storage
Impact of Storage.doc (Size: 32 KB / Downloads: 13)
Abstract:
The volume of worldwide digital content has increased nine-fold within the last five years, and this immense growth is predicted to continue in foreseeable future eaching 8ZB already by 2015. Traditionally, in order to cope with the growing demand for storage capacity, organizations proactively built and managed their private storage facilities. Recently, with the proliferation of public cloud infrastructure offerings, many organizations, instead, welcomed the alternative of outsourcing their storage needs to the providers of public cloud storage services. The comparative cost-efficiency of these two alternatives depends on a number of factors, among which are e.g. the prices of the public and private storage, the charging and the storage acquisition intervals, and the predictability of the demand for storage. In this paper, we study how the cost-efficiency of the private vs. public storage depends on the acquisition interval at which the organization re-assesses its storage needs and acquires additional private storage. The analysis in the paper suggests that the shorter the acquisition interval, the more likely it is that the private storage solution is less expensive as compared with the public cloud infrastructure. This phenomenon is also illustrated in the paper numerically using the storage needs encountered by a university back-up and archiving service as an example. Since the acquisition interval is determined by the organization’s ability to foresee the growth of storage demand, by the provisioning schedules of storage equipment providers, and by internal practices of the organization, among other factors, the organization owning a private storage solution may want to control some of these factors in order to attain a shorter acquisition interval and thus make the private storage (more) cost-efficient..
Existing System:
To cope with the growing demand for storage, organizations may proactively build their private storage capacity; in this scenario, the organizations periodically estimate their future demand for storage and then acquire and manage the storage infrastructure internally. Alternatively, the organizations may opt for outsourcing their storage to the providers of public cloud infrastructure services, such as Amazon Simple Storage Service (S3), Box.com, Apple iCloud, etc. The use of such cloud-based storage services gives the organization the flexibility of rapidly increasing its storage capacity as the demand for the storage grows, as well as the possibility to pay only for the volume of storage the organization actually uses within each charging period. These benefits have rendered the cloud storage services popular among companies: for instance, in October 2011 Amazon reported half a trillion of stored objects in its S3 service, representing an immense 187% combined annual growth rate (CAGR) between 2006 and 2011.
Proposed System:
The cost-efficiency of the public vs. private storage depends on a number of factors, such as the premium charged by the provider of public cloud infrastructure, the charging period (for the public storage) and the storage acquisition interval (for the private storage), the intensity of incurred data communications, the predictability of the growth of storage needs, etc. In this paper, we study the effect of the private storage acquisition interval on the cost efficiency of the private vs. public storage. This interval can be determined by the organization’s ability to foresee of the storage equipment provider, by internal practices of the organization, etc. The paper analytically shows that the shorter the interval at which the organization re-assesses its storage needs and acquires additional storage, the more likely it is that the private storage solution is less expensive as compared with the public cloud infrastructure. Numerical experiments are employed in order to illustrate this dependency using the storage needs encountered by a university back-up and archiving service as an example.
Private Users:
For the private storage, the relevant cost constituents include the cost of hardware and software acquisition, integration, configuration, upgrade costs, as well as the
recurring costs of renting floor space, power, bandwidth, and the cost of administration and maintenance. Thus, the cost of the private storage is a function of the demand as well as its growth pattern and its predictability, the time interval between storage acquisitions, and the pricing of the needed equipment, software, and personnel, along some other expenses.
Public Users:
On the other hand, for the public cloud storage, the cost constituents include the usage-dependent costs of storage capacity, data transfer, and input/output requests (based on the pricing set by Amazon S3). Depending on the charging policy of the provider, the cost of the storage may be determined by the maximum volume of storage occupied during the charging period: for instance.
Linear Programming Solution:
The cost-optimal allocation of individual computing tasks to the private and public cloud resources was also approached as a multi-integer linear programming problem in . Based on the results of a simulation study, the authors found little or no cost benefits in offloading the peaks of the workload, though the preliminary character of the study and the complex nature of the optimization model make it difficult to interpret the results.