Stergios V. Anastasiadis

Learn More
Parallel applications can be executed using the idle computing capacity of workstation clusters. However, it remains unclear how to most eeectively schedule the processors among diierent applications. Processor scheduling algorithms that were successful for shared-memory machines have proven to be inadequate for distributed memory environments due to the(More)
We introduce an algorithm that uses buffer space available at the server for smoothing disk transfers of variable bit-rate streams. Previous smoothing techniques prefetched stream data into the client buffer space, instead. However, emergence of personal computing devices with widely different hardware configurations means that we should not always assume(More)
In dynamic environments with frequent content updates, we require online full-text search that scales to large data collections and achieves low search latency. Several recent methods that support fast incremental indexing of documents typically keep on disk multiple partial index structures that they continuously update as new documents are added. However,(More)
Scalable network servers are increasingly identiied as a critical component in the exponential growth of the Internet. We focus on media servers for variable bit rate streams and study the scalability of alternative disk striping policies, previously known and new. In contrast to results of previous studies, we show that the highest sustained number of(More)
Explosive growth in online services has recently renewed the interest for building modular and eecient network server systems. System design complications coupled with excessive expectations from technological progress previously discouraged the development of media servers eeciently supporting video streams with variable bit rates. In this paper, we(More)
In a system offering on-demand real-time streaming of media files, data striping across an array of disks can improve load balancing, allowing higher disk utilization and increased system throughput. However, it can also cause complete service disruption in the case of a disk failure. Reliability can be improved by adding data redundancy and reserving extra(More)
Synchronous small writes play a critical role in the reliability and availability of file systems and applications that use them to safely log recent state modifications and quickly recover from failures. However, storage stacks usually enforce page-sized granularity in their data transfers from memory to disk. We experimentally show that subpage writes may(More)
In the present paper, we examine the problem of supporting application-specific computation within a network file server. Our objectives are (i) to introduce an easy to use yet powerful architecture for executing both custom-developed and legacy applications close to the stored data, (ii) to investigate the performance improvement that we get from data(More)
Whole-file transfer is a basic primitive for Internet content dissemination. Content servers are increasingly limited by disk arm movement given the rapid growth in disk density, disk transfer rates, server network bandwidth, and content size. Individual file transfers are sequential, but the block access sequence on a content server is effectively random(More)
—We investigate the problem of smoothing multiplexed network traffic when either a streaming server transmits data to multiple clients or a storage server accesses data from multiple storage devices or other servers. We introduce efficient algorithms for lexicographically optimally smoothing the aggregate bandwidth requirements over a shared network link.(More)