Multiple Storage Systems Research Articles

Valuation of Multiple Hyro Reservoir Storage Systems in Competitive Electricity Markets

Increasing renewable generation results in growing supply uncertainty. By now hydrostorages are the most efficient way of smoothing uncertain power supply. In liberalized and competitive markets the valuation of hydro storages investment projects needs to take the market information and therefore the uncertainty of electricity prices into account in investment valuation. Besides the investment in new pump storage facilities the extension of existing storage sites may be an opportunity. However, the correct valuation of multiple reservoir storage systems within an uncertain market is a valuation problem with high dimensionality. We propose an approach that applies numerically constructed multinomial recombining price trees to reduce the problem dimension. We present results for a representative case study. In doing so, we apply a spot price model which accounts for the price fundamentals as well as for the price stochastic.

The personal internet

PeCMan, the Personal Content Manager, is a content access gateway, aggregator, indexing, and sharing tool for all of a user's personally relevant content on the Internet, e.g., all the content a user has created, content that was explicitly shared by others, or publicly available Internet content of specific interest. PeCMan aggregates access to multiple network-based storage systems, services, or other “objects” by their reference. Examples of such objects are photographs, music, e-mail, text documents, or any addressable object on the Internet. The aggregated storage acts as a virtual read-write drive in which PeCMan addresses individual objects by reference, typically encoded in uniform resource locators (URLs). To address content in Web applications such as Google Docs, Flickr, and YouTube, the URL is based on the corresponding application programming interface (API), while content on a user's home machine's disk is addressed via a locally installed software driver supporting Web-based distributed authoring and versioning (WebDAV). This paper describes the motivation, design, and implementation prototype of PeCMan. é 2010 Alcatel-Lucent.

Easy on that trigger dad: a study of long term family photo retrieval

We examine the effects of new technologies for digital photography on people’s longer term storage and access to collections of personal photos. We report an empirical study of parents’ ability to retrieve photos related to salient family events from more than a year ago. Performance was relatively poor with people failing to find almost 40% of pictures. We analyze participants’ organizational and access strategies to identify reasons for this poor performance. Possible reasons for retrieval failure include: storing too many pictures, rudimentary organization, use of multiple storage systems, failure to maintain collections and participants’ false beliefs about their ability to access photos. We conclude by exploring the technical and theoretical implications of these findings.

Enriched namespace to support content-aware authorization policies

In the near future, data on the order of hundreds of Petabytes will be spread in multiple storage systems worldwide dispersed in, potentially, billions of replicated data items. Users, typically, are agnostic about the location of their data and they want to get access by either specifying logical names or using some lookup mechanism.A global namespace is a logical layer that allows the view of data resources independently from the physical location. Usually, the naming scheme is designed to be easily interpreted by humans and it is organized into a purely user-defined directory hierarchy. Within this model, a data resource is uniquely addressed by file name and path. Nevertheless, this hierarchical structures of logical namespace lacks adequate flexibility to manage sophisticated organization of data. In particular the implicit classification of the data item derived from the path is not enough meaningful to classify data objects when different orthogonal dimensions are considered.In this paper we expose an enriched namespace able to support a new type of data access authorization policy based on tags. The tags are organized in well-defined hierarchies providing a simple representation of the domain ontology. Only authorized users can label data resources with different tags taken from the domain tag hierarchies. In this way an overlay of classical hierarchical structure of logical namespace with faceted hierarchical tags provides a semantics classification of data entities. Authorization policies defined in respect of tags are content-aware.

Building Preservation Environments with Data Grid Technology

Preservation environments for digital records are successful when they can separate the digital record from any dependence on the original creating infrastructure. Data grid technology, which supports the management of records that are located on multiple storage systems, provides the software needed for infrastructure independence. This article provides a description of how data grid technology can be used to support preservation processes and of existing preservation environments that are based upon data grids.

Management of special services — designing for a changing world

COSMOSS, BT‘s customer-oriented system for the management of special services, was implemented in early 1994. It is a large 3270-based multiple virtual storage (MVS) system using CICS, DB2 and BT Middleware. Though seen by some as a legacy system cloned from the customer service system (CSS), COSMOSS is very forward looking in its attempts to anticipate and accommodate change. This paper discusses the COSMOSS design approach and in particular how it tackles problems associated with the inevitability of change.