Modern storage systems use thousands of inexpensive disks to meet the storage requirement of applications. To enhance the data availability, some form of redundancy is used. For example, conventional RAID-5 systems pr...
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ISBN:
(纸本)9781450302111
Modern storage systems use thousands of inexpensive disks to meet the storage requirement of applications. To enhance the data availability, some form of redundancy is used. For example, conventional RAID-5 systems provide data availability for single disk failure only, while recent advanced coding techniques such as row-diagonal parity (RDP) can provide data availability with up to two disk failures. To reduce the probability of data unavailability, whenever a single disk fails, disk recovery (or rebuild) will be carried out. We show that conventional recovery scheme of RDP code for a single disk failure is inefficient and suboptimal. In this paper, we propose an optimal and efficient disk recovery scheme, Row-Diagonal Optimal recovery (RDOR), for single disk failure of RDP code that has the following properties: (1) it is read optimal in the sense that it issues the smallest number of disk reads to recover the failed disk;(2) it has the load balancing property that all surviving disks will be subjected to the same amount of additional workload in rebuilding the failed disk. We carefully explore the design state space and theoretically show the optimality of RDOR. We carry out performance evaluation to quantify the merits of RDOR on some widely used disks.
Modern storage systems use thousands of inexpensive disks to meet the storage requirement of applications. To enhance the data availability, some form of redundancy is used. For example, conventional RAID-5 systems pr...
详细信息
ISBN:
(纸本)9781450300384
Modern storage systems use thousands of inexpensive disks to meet the storage requirement of applications. To enhance the data availability, some form of redundancy is used. For example, conventional RAID-5 systems provide data availability for single disk failure only, while recent advanced coding techniques such as row-diagonal parity (RDP) can provide data availability with up to two disk failures. To reduce the probability of data unavailability, whenever a single disk fails, disk recovery (or rebuild) will be carried out. We show that conventional recovery scheme of RDP code for a single disk failure is inefficient and suboptimal. In this paper, we propose an optimal and efficient disk recovery scheme, Row-Diagonal Optimal recovery (RDOR), for single disk failure of RDP code that has the following properties: (1) it is read optimal in the sense that it issues the smallest number of disk reads to recover the failed disk;(2) it has the load balancing property that all surviving disks will be subjected to the same amount of additional workload in rebuilding the failed disk. We carefully explore the design state space and theoretically show the optimality of RDOR. We carry out performance evaluation to quantify the merits of RDOR on some widely used disks.
Multicasting is an efficient communication tool for use ill multi-point applications such as conferencing and information distribution. Ill ad hoc networks, node mobility causes frequent changes of network topology, a...
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Multicasting is an efficient communication tool for use ill multi-point applications such as conferencing and information distribution. Ill ad hoc networks, node mobility causes frequent changes of network topology, and re-construction of the multicast, tree in all efficient and effective manner becomes a critical issues. In case of link breakage, most of the multicast tree construction protocols available presently require either a total re-build of the tree or to reconnect a disjoined node back to the multicast tree via the shortest path which may disrupt, the, optimising factors, such as energy consumption delay Or Cost, Used ill the building of the original tree. Ill this papers we introduce a computationally efficient recover algorithm which will also minimise the power consumption oil the tree.
Intelligent optical networks support real-time automatic connection configuration and recovery, which give rise to another new set of problems, such as the unsureness of resource reservation and the uncertainty of con...
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ISBN:
(纸本)0780395387
Intelligent optical networks support real-time automatic connection configuration and recovery, which give rise to another new set of problems, such as the unsureness of resource reservation and the uncertainty of connection recovery. In view of those facts, we examine current optical network protection and restoration schemes, and propose a connection survivable resource reservation algorithm based on fault simulation. By automatic simulating one link failure or multi share risk link group failures combination, this algorithm can allocate enough backup resources, which make the networks can survive any 1 similar to 3 node or link failures.
A new method, to improve the lateral resolution of differential profile measurement is proposed, together with a related profile recovery algorithm. In this method, the lateral resolution will not be constrained to th...
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ISBN:
(纸本)0819446866
A new method, to improve the lateral resolution of differential profile measurement is proposed, together with a related profile recovery algorithm. In this method, the lateral resolution will not be constrained to the distance between two differential probes. It-can be a fraction of the distance and is affected by the. scanning resolution. In the corresponding algorithm to recover a profile, d is the probes distance, d(r) is the scanning resolution, and d(r) = d/N, where N is the number of groups separated from, the difference data set. Integration is applied to every group to build a profile. Finally, spline smoothing regression is used to the profiles to find translations between them to obtain the whole profile. Computer stimulation was used to examine the effectiveness of the proposed recovery algorithm and good accuracy was achieved.
This paper presents a recovery algorithm for self-stabilizing communication protocols. It first describes some concepts and a formal description method for the algorithm. Then it proposes the algorithm procedures, pro...
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This paper presents a recovery algorithm for self-stabilizing communication protocols. It first describes some concepts and a formal description method for the algorithm. Then it proposes the algorithm procedures, proves its correctness and analyses its complexity. Finally, it also verifies the availability and efficiency of the algorithm by illustrating an example protocol with multi-processes.
The problem of rollback recovery is traditionally approached using a model oriented to packet delivery. Instead, we introduce a model centered around complex sessions, and we explain why this model is more appropriate...
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ISBN:
(纸本)0769516718
The problem of rollback recovery is traditionally approached using a model oriented to packet delivery. Instead, we introduce a model centered around complex sessions, and we explain why this model is more appropriate. Using this model, we extract a basic coordination scheme that is common to the three distributed activities that compose rollback recovery: checkpointing, rollback and disposal. The basic coordination scheme is refined to describe each of the three activities.
The class of chain graphs (CGs) involving both undirected graphs (=Markou networks) and directed acyclic graphs (= Bayesian networks) was introduced in middle eighties for description of probabilistic conditional inde...
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The class of chain graphs (CGs) involving both undirected graphs (=Markou networks) and directed acyclic graphs (= Bayesian networks) was introduced in middle eighties for description of probabilistic conditional independence structures. Every class of Markov equivalent CGs (that is, CGs describing the same conditional independence structure) has a natural representative which is called the largest CG. The paper presents a recovery algorithm which on the basis of the conditional independence structure given by a CG (in the form of a dependency model) finds the largest CG representing the corresponding class of Markov equivalent CGs. As a by-product a graphical characterization of graphs which are the largest CGs (for a class of Markov equivalent CGs) is obtained, and a simple algorithm changing every CG into the largest CG of the corresponding equivalence class is given. (C) 1997 Elsevier Science Inc.
At the present time, block-transform coding is probably the most popular approach for image compression, For this approach, the compressed images are decoded using only the transmitted transform data, In this paper, w...
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At the present time, block-transform coding is probably the most popular approach for image compression, For this approach, the compressed images are decoded using only the transmitted transform data, In this paper, we formulate image decoding as an image recovery problem, According to this approach, the decoded image is reconstructed using not only the transmitted data but, in addition, the prior knowledge that images before compression do not display between-block discontinuities. A spatially adaptive image recovery algorithm is proposed based on the theory of projections onto convex sets. Apart from the data constraint set, this algorithm uses another new constraint set that enforces between-block smoothness, The novelty of this set is that it captures both the local statistical properties of the image and the human perceptual characteristics, A simplified spatially adaptive recovery algorithm is also proposed, and the analysis of its computational complexity Is presented, Numerical experiments are shown that demonstrate that the proposed algorithms work better than both the JPEG deblocking recommendation and our previous projection-based image decoding approach.
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