  In this paper we present the Chelonia storage cloud middleware. It was
designed to fill the requirements gap between those of large, sophisticated
scientific collaborations which have adopted the grid paradigm for their
distributed storage needs, and of corporate business communities which are
gravitating towards the cloud paradigm. The similarities to and differences
between Chelonia and several well-known grid- and cloud-based storage solutions
are commented. The design of Chelonia has been chosen to optimize high
reliability and scalability of an integrated system of heterogeneous,
geographically dispersed storage sites and the ability to easily expand the
system dynamically. The architecture and implementation in term of web-services
running inside the Advanced Resource Connector Hosting Environment Dameon (ARC
HED) are described. We present results of tests in both local-area and
wide-area networks that demonstrate the fault-tolerance, stability and
scalability of Chelonia.
