Desktop virtualization is a very hot concept in both industry and academic communities. Since virtualized desktop system is based on multiple virtual machines (VM), it is necessary to design a distributed storage syst...
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Desktop virtualization is a very hot concept in both industry and academic communities. Since virtualized desktop system is based on multiple virtual machines (VM), it is necessary to design a distributed storage system to manage the VM images. In this paper, we design a distributed storage system, VMStore, by taking into account three important characteristics: high performance VM snapshot, booting optimization from multiple images and redundancy removal of images data. We adopt a direct index structure of blocks for VM snapshots to speed up VM booting performance significantly; provide a distribute storage structure with good bandwidth scalability by dynamically changing the number of storage nodes; and propose a data preprocessing strategy with intelligent object partitioning techniques, which would eliminate duplication more effectively. Performance analysis for VMStore focuses on two metrics: the speedup of VM booting and the overhead of de-duplication. Experimental results show the efficiency and effectiveness of VMStore.
Recently much attention has been paid to semantic overlay networks for information retrieval in large scale peer-to-peer networks,and much research work on semantic overlay protocols and searching algorithms has been ...
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Recently much attention has been paid to semantic overlay networks for information retrieval in large scale peer-to-peer networks,and much research work on semantic overlay protocols and searching algorithms has been done and the results indicate that semantic overlay is efficient for content searching in peer-to-peer ***,very limited work has been done to analyze and evaluate the characteristics of semantic overlay *** this paper we identify a natural property of semantic overlay networks,the community *** propose a mathematical model to evaluate the property of community structure of semantic P2P overlay networks.A heuristic algorithm is designed to optimize the community *** the evaluation model we compare the SemreX semantic overlay with the Gnutella *** demonstrate that a SemreX overlay network has the distinctive community structure feature,while a Gnutella-like network does *** also simulate a simple flooding protocol in both overlays to show that the overlay with community structure is more efficient for content searching.
Recent advance of virtualization technology provides a new approach to check-point/restart at the virtual machine(VM) *** contrast to traditional process-level checkpointing,checkpointing at the virtualization layer b...
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Recent advance of virtualization technology provides a new approach to check-point/restart at the virtual machine(VM) *** contrast to traditional process-level checkpointing,checkpointing at the virtualization layer brings up several advantages,such as compatibility,transparence,flexibility and ***,because the virtualization layer has little semantic knowledge about the operation {1. and the applications running atop,VM-layer checkpointing requires saving the entire operating {1. state rather than a single *** overhead may render the approach *** reduce the size of VM checkpoint,in this paper we propose a page eviction scheme and an incremental checkpointing mechanism to avoid saving unnecessary VM pages in the *** keep the {1. online transparently,we propose a live checkpointing mechanism by saving the memory image in a copy-on-write(COW) *** implement the performance optimization mechanisms in a prototype {1.,called *** results with a group of representative applications show that our page eviction scheme and incremental checkpointing can significantly reduce the checkpoint file size by up to 87% and shorten the total checkpointing/restart time by a factor of up to 71.,in comparison with the Xens default checkpointing *** observed application downtimes due to checkpointing can be reduced to as small as 300 ms.
Cloud computing suffers from a number of problems in terms of security *** and integrity play an important role in the security field and numerous concerns have been raised to recognizeor protect any tampering with ex...
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Cloud computing suffers from a number of problems in terms of security *** and integrity play an important role in the security field and numerous concerns have been raised to recognizeor protect any tampering with exchanges of text between two entities(sender and receiver)within the cloud *** schemes in this area can be vulnerable to well known methods of attack such as replay attack,forgery attack,dictionary,insider,and modification attacks.A robust scheme is therefore required to detect or prevent any modification or manipulation of a message during *** this paper,we propose a new message authentication code(MAC)based on feature extraction of the user's iris in order to assure the integrity of the user's *** are extracted from the user's iris to generate a message code for each user's login and to prohibit malicious attacks such as replay,forgery and insider *** proposed scheme enjoysseveral important security attributes such as a user's one time bio-key,robust message anonymity,data integrity for a user's message,phase key agreement,bio-key management,and one time message code for each user's ***,our security analysis and experimental results demonstrate and prove the invulnerability and efficiency of our proposed scheme.
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