Replication Placement on Disks

Replication Placement on Disks

Phillip K.C. Tse (University of Hong Kong, China)
DOI: 10.4018/978-1-59904-225-1.ch007
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Abstract

When extra storage space is available on the striping disks being described in the last chapter, the storage system may keep extra copies of the stored objects to enhance the performance of the storage system. If any one of the copy or the original copy is corrupted, the corrupted copy can possibly be recovered by comparison with its replicas. The replication strategy thus increases reliability of the storage system by applying redundancy on the stored objects. Extra copies of objects may be created and stored on the storage system to increase the storage system performance. The presence of replicas on light loading disks may be able to reduce the period of time that an object is inaccessible. Thus, the replication strategy increases the availability of the stored objects. The replication strategy can have several advantages. First, the replica on idle disks can increase the availability of data on corrupted and busy disks. Second, the replica on local server can reduce the network load to access objects from remote servers. Third, the replica on local server can also reduce the need to wait for the filling of initial buffer prior to consumption. Fourth, replica can avoid disk multitasking by avoiding the need to serve multiple streams from the same disk head. We will describe the streaming redundant array of inexpensive disks (RAID) method that increases availability and fault tolerance in the next section. After that, we present the Lancaster storage server to reduce network load. Then, we show two data replication methods to reduce start-up latency. Afterwards, we explain how the data replication method can avoid disk multitasking. Before we conclude this chapter, we describe the replication method that balances the space and workload of storage devices.

Complete Chapter List

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Table of Contents
Foreword
Clement Leung
Acknowledgment
Chapter 1
Introduction  (pages 1-4)
Phillip K.C. Tse
This book explains the techniques to store and retrieve multimedia information in multimedia storage systems. It describes the internal architecture... Sample PDF
Introduction
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Chapter 2
Phillip K.C. Tse
To start this book, I shall first describe the characteristics of multimedia data. Then, some multimedia applications are listed. After these, I... Sample PDF
Multimedia Information
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Chapter 3
Phillip K.C. Tse
Multimedia systems are similar to traditional computer systems in terms of their architectures. Both types of systems have central processing unit... Sample PDF
Storage System Architectures
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Chapter 4
Phillip K.C. Tse
In the previous chapter, we see that the performance of a storage system depends on the amount of data being retrieved. The size of multimedia... Sample PDF
Data Compression Techniques and Standards
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Chapter 5
Phillip K.C. Tse
The access pattern on each multimedia object can have very different characteristics. Some multimedia objects are more popular and they are more... Sample PDF
Statistical Placement on Disks
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Chapter 6
Striping on Disks  (pages 101-113)
Phillip K.C. Tse
Multimedia streams need continuous data supply. The aggregate data access requirement of many multimedia streams imposes very high demand on the... Sample PDF
Striping on Disks
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Chapter 7
Phillip K.C. Tse
When extra storage space is available on the striping disks being described in the last chapter, the storage system may keep extra copies of the... Sample PDF
Replication Placement on Disks
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Chapter 8
Phillip K.C. Tse
Most existing storage servers store data stripes on magnetic hard disks. These magnetic hard disks are accessed by moving the disk heads to random... Sample PDF
Constraint Allocation on Disks
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Chapter 9
Tertiary Storage Devices  (pages 145-155)
Phillip K.C. Tse
The main objective of the tertiary storage level is to provide huge storage capacity at low cost. Several types of storage devices are available to... Sample PDF
Tertiary Storage Devices
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Chapter 10
Phillip K.C. Tse
The contiguous placement is the most common method to place traditional data files on tertiary storage devices. The storage space in the media units... Sample PDF
Contiguous Placement on Hierarchical Storage Systems
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Chapter 11
Phillip K.C. Tse
We have described the contiguous placement in the previous chapter and the statistical strategy to place objects on disks in Chapter IV. In this... Sample PDF
Statistical Placement on Hierarchical Storage Systems
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Chapter 12
Phillip K.C. Tse
The data striping technique has been successfully applied on disks to reduce the time to access objects from the disks as shown in Chapter VI.... Sample PDF
Striping on Hierarchical Storage Systems
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Chapter 13
Phillip K.C. Tse
Multimedia objects are stored on hierarchical storage systems (HSS). The objects are large in size but the access latency of HSS is high. It is... Sample PDF
Constraint Allocation on Hierarchical Storage Systems
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Chapter 14
Phillip K.C. Tse
Disk scheduling changes the sequence order to serve the requests that are waiting in the queue. While data placement reduces the access time of a... Sample PDF
Scheduling Methods for Disk Requests
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Chapter 15
Phillip K.C. Tse
Multimedia storage systems store data objects and receive streams of requests from the multimedia server. When a client wishes to display an object... Sample PDF
Feasibility Conditions of Concurrent Streams
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Chapter 16
Phillip K.C. Tse
In the previous chapter, we have presented the feasibility condition to serve request streams concurrently. In this chapter, we describe the... Sample PDF
Scheduling Methods for Request Streams
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Chapter 17
Staging Methods  (pages 263-271)
Phillip K.C. Tse
When data are stored in the tertiary storage devices, the tape drives shall read them from the tapes using the input/output (I/O) operations. Due to... Sample PDF
Staging Methods
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Chapter 18
Time Slicing Method  (pages 272-279)
Phillip K.C. Tse
Tertiary storage devices provide huge storage capacity at low cost. Multimedia objects stored on the tertiary storage devices are accessed with high... Sample PDF
Time Slicing Method
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Chapter 19
Normal Pipelining  (pages 280-288)
Phillip K.C. Tse
Multimedia objects can be stored on tertiary storage devices to provide large storage capacity at low cost. The staging method retrieves the whole... Sample PDF
Normal Pipelining
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Chapter 20
Phillip K.C. Tse
Multimedia objects that are stored on tertiary storage devices enjoy the large storage capacity at low cost. These objects may be retrieved using... Sample PDF
Space Efficient Pipelining
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Chapter 21
Segmented Pipelining  (pages 299-319)
Phillip K.C. Tse
The robotic tape library and optical jukebox provide huge and cheap capacity for the storage of multimedia objects. The stored objects may be... Sample PDF
Segmented Pipelining
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Chapter 22
Memory Caching Methods  (pages 325-340)
Phillip K.C. Tse
The objective of data caching and object caching is to improve the performance in accessing multimedia objects from their storage. An efficient... Sample PDF
Memory Caching Methods
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Chapter 23
Stream Dependent Caching  (pages 341-367)
Phillip K.C. Tse
Caching has been successfully implemented on the Internet to reduce workload on the content server and the Internet. We have seen in the last... Sample PDF
Stream Dependent Caching
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Chapter 24
Cooperative Web Caching  (pages 368-382)
Phillip K.C. Tse
Most clients are placed behind the proxy servers on the Internet. Proxy servers have the disk cache space, network bandwidth, and availability to... Sample PDF
Cooperative Web Caching
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About the Author