Dimitrios E. Pendarakis

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The IP multicast model allows scalable and efficient multi-party communication, particularly for groups of large size. However, deployment of IP multicast requires substantial infrastructure modifications and is hampered by a host of unresolved open problems. To circumvent this situation, we have designed and implemented ALMI, an application level group(More)
Resource provisioning in compute clouds often require an estimate of the capacity needs of Virtual Machines (VMs). The estimated VM size is the basis for allocating resources commensurate with workload demand. In contrast to the traditional practice of estimating the VM sizes individually, we propose a joint-VM sizing approach in which multiple VMs are(More)
Virtualization technology is becoming increasingly common in datacenters, since it allows for collocation of multiple workloads, consisting of operating systems, middleware and applications, in different virtual machines (VMs) on shared physical hardware platforms. However, when coupled with the ease of VM migration, this trend increases the potential(More)
In this paper we present our experience in building the Research Compute Cloud (RC2), a cloud computing platform for use by the worldwide IBM Research community. Within eleven months of its official release RC2 has reached a community of 631 users spanning 34 countries , and serves on average 350 active users and 1800 active VM instances per month. Besides(More)
What is the impact of autocorrelation of Variable Bit Rate (VBR) video sources on real-time scheduling algorithms? Our results show that the impact of long term, or interframe, au-tocorrelation is negligible, while the impact of short term, or intraframe, autocorrelation can be signiicant. Such results are essentially independent of the video coding scheme(More)
The trusted virtual data center (TVDc) is a technology developed to address the need for strong isolation and integrity guarantees in virtualized environments. In this paper, we extend previous work on the TVDc by implementing controlled access to networked storage based on security labels and by implementing management prototypes that demonstrate the(More)
— We consider a multiuser network that is shared by noncooperative users. Each user sets up virtual paths that optimize its own selfish performance measure. This measure accounts for the guaranteed call level quality of service, as well as for the cost incurred for reserving the resource. The interaction among the user strategies is formalized as a(More)
— This paper describes a general methodology for constructing accurate source models of long sequences (full-length movies) of full-motion compressed VBR (variable bit rate) video, directly from empirical data sets of observed bit rate (frame size) records. The main idea is to first cluster scenes into classes and use TES (transform-expand-sample) processes(More)
We propose a new policy for virtual path bandwidth allocation in broadband networks. Based on a threshold scheme, our policy handles the inherent tradeoo between bandwidth utilization and processing costs. In each virtual path controller the thresholds are chosen so as to keep bandwidth utilization high, while obtaining a low rate of processing requests.(More)