| With the social development and progress, the development of information technology is getting faster and faster, especially the rapid development of the Internet and personal digital products has changed people’s way of getting information. A few years ago, the development of multi-media technologies lead people into media era instead of recoding by pens and paper.And now, it is time for everyone to post his self-media to the public. The explosive growth of information caused a great deal of pressure, one is the rapid growth in the amount of information on the increasingly high demand for storage capacity, the second is the increasing value of the data itself, it is even far moreprecious than the value of the storage medium. As a result, requirements to storage reliability are of importance.As it is necessary to rise the the reliability of large-capacity storage system, the original coding techniques began to be limited.For RS code in DVD and magnetic hard drive, BCH code in SLC SSD and erasure codes in distributed storage system are almost close to their limitations, it is very necessary for a new coding method in storage system. It is known that LDPC codes are the codes nearest to Shannon capacity limit until now, but because of encoding and decoding is more complex, it has not come into service in the beginning. With the rapid development of semiconductor technology in recent years, it has been possible to encode and decode LDPC codes based on VLSI chips. As a result, after being applied in communications, LDPC codes start to be used in storage system. This paper is based on these considerations, and we focus on LDPC codes in various storage systems.Facing the serious challenge of hard disk storage systems currently, optical storage system always gets its market share by its advantages in the storage system. The advantages of optical storage can be summarized as the following:the unit cost will be very low when bulk copy, optical storage system can save important data for as long as100years; data on recordable once discs can not be erased by fault, the stored information will never be lost, so optical storage system is ideal for permanent preservation of personal data. As the next generation of high-density optical disk storage system’s data density is much higher than other early low-density optical storage system, like DVDs, RS code is powerless which is widely used in DVD in recent years. The randomly constructed LDPC codes can be constructed by optimal constructing matrix which is filtered by computer. As a result, LDPC codes can replace the RS code with a better reliability in high-density optical storage system. This paper studied on the feasibility and practicality of randomly constructed LDPC codes in-depth demonstration firstly.It is also indicated that randomly constructed LDPC codes can be used for high density optical disk storage system, and it can be effectively improved the reliability of the high density optical disk storage system.Due to there being no mechanical equipment and being based on semiconductor memory, the solid-state disk catches people’s sight by its high speed, high IOPS in commercial storage systems and personal storage systems market. However, non-resistant and asymmetric read-and-write speed are the two fatal factors of SSDs. This paper is constructed from the view of the QC-LDPC error correction code which is suitable for solid-state disk storage system. And we use shortening technology at the expense of reduction of code rate. The shorten QC-LDPC is suitable for solid-state disk, and it can help improving the reliability of solid-state disk. In addition, we also develop a technique for solid-state disk, which is now facing another reliability challenge, by a new fine-grained data reconstruction algorithm.In this case, erasure life can be effectively extended of multi-level cell (MLC) and3-level cell (TLC) in this paper.Distributed storage system is a milestone in the history of storage system. It is not only the advantages of RAID, which is based on cheap desktop hard disks to build high performance and high reliability storage systems, but also connects to other storage subsystems through network, or even builds high-performance wild-area-network-based storage systems. However, researchers in the field of distributed storage system have focused on reliability of distributed storage while economic value is less studied in the past. Relative to the horizontal erasure codes and vertical erasure codes, which are widely used in distributed storage system, LDPC codes have a stronger error correction and linear decoding time. In this paper, study of LDPC codes will extend the field of distributed storage system. We first studied LDPC code suitable for distributed storage systems, and then proposed the optimization strategy between erasure coding strategy and replication strategy through these different costs per unit in use of game theory. Furthermore, Sharp value is given following Nash equilibrium in distributed storage system.In summary, key technologies are studied which are applied to storage systems using LDPC codes in this paper. LDPC codes in optical storage system, solid-state disk storage system and distributed storage system are all studied, and we have made progress, which further expand the scope of LDPC codes. |
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