Manolis Marazakis

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EUROSERVER is a collaborative project that aims to dramatically improve data centre energy-efficiency, cost, and software efficiency. It is addressing these important challenges through the coordinated application of several key recent innovations: 64-bit ARM cores, 3D heterogeneous silicon-on-silicon integration, and fully-depleted silicon-on-insulator (FD(More)
Flash-based solid state drives (SSDs) offer superior performance over hard disks for many workloads. A prominent use of SSDs in modern storage systems is to use these devices as a cache in the I/O path. In this work, we examine how transparent, online I/O compression can be used to increase the capacity of SSD-based caches, thus increasing the(More)
Workloads in distributed database applications consist of queries and transactions. In order to address performance requirements, distributed transaction processing systems have to deal with two related issues: transaction routing and scheduling. Due to the distribution of data objects among nodes and the access cost incurred by remote accesses, efficient(More)
Flash-based solid state drives (SSDs) exhibit potential for solving I/O bottlenecks by offering superior performance over hard disks for several workloads. In this work we design Azor, an SSD-based I/O cache that operates at the block-level and is transparent to existing applications, such as databases. Our design provides various choices for associativity,(More)
In this work we examine how transparent compression in the I/O path can improve space efficiency for online storage. We extend the block layer with the ability to compress and decompress data as they flow between the file-system and the disk. Achieving transparent compression requires extensive metadata management for dealing with variable block sizes,(More)
In this paper we describe a prototype that supports end to end QoS for applications invoking services over an ATM switch. The required resources are allocated to applications via auctions taking place in two independent markets. We investigate the effects of market independence in the behavior of the system, and report results of experiments with(More)
Volunteer computing is becoming a new paradigm not only for the computational grid, but also for institutions using production-level data grids because of the enormous storage potential that may be achieved at a low cost by using commodity hardware within their own computing premises. However, this novel "Desktop Data Grid" depends on a set of widely(More)
The qualitative and quantitative description of the workload of a system is very important for capacity planning and performance management. In large-scale transaction processing systems, dynamic workload control algorithms are applied to optimize system performance. Such algorithms can bene t from the results of workload clustering algorithms that(More)
This paper discusses the requirements of current and emerging large-scale distributed applications and emphasizes the need for a common infrastructure to support them. A design for an infrastructure that aims at satisfying these requirements is presented. Moreover, it is shown how key aspects of important large-scale applications can exploit the services(More)
Workflow management systems are developed to support and automate the execution of business processes, by assigning tasks to agents according to the workflow specification. Current state-of-the-art workflow systems are mainly concerned with the routing and assignment of tasks, providing little support for tasks related to administration and management. This(More)