Volume holographic storage with high storage density and access rate has excellent potential for large-scale data storage. However, data reliability is facing challenges and has become a main concern from various noise interference. In holographic storage systems with phase modulated, high raw bit error rates (RBER) are induced by optical noise, electrical noise, intra and inter page interference, reducing data reliability. In this paper, we exploits low-density parity-check (LDPC) coding with remarkable error correction capability to improve data reliability and capacity with minimizing read latency for phase modulated holographic storage. LDPC coding has a stronger error correction capability by adopting soft decision decoding with log-likelihood ratio (LLR) information. As a result, the bit error rates (BER) can be reduced and data reliability is significantly enhanced. In the process of the evaluation, we first count the variation of RBER with phase modulated under different single-to-noise ratio (SNR). Then, after using LDPC coding, we compare the sharpness of the modulated two-dimensional data pages to validate the effectiveness of utilizing LDPC coding. Moreover, we study the internal relationship between phase reconstruction with iterative Fourier transform algorithms and LDPC coding. The decoding iteration times and the number of Fourier iterations are counted. Simulation results show that LDPC coding can improve data reliability by decreasing BER.
KEYWORDS: Data storage, Solid state physics, Computing systems, Data centers, Inspection, Servomechanisms, Manufacturing, Solid state electronics, Modulation, Optics manufacturing
Recently, high-energy consumption has become a serious concern for both storage servers and data centers. Recent
research studies have utilized the short response times of multiple speed disks to decrease energy consumption.
However, very few manufactures can produce the multiple speeds hard disk because of its complexity. The main
limitation to MAID system is that we must assume the frequently accessed data is less than 5%, in fact, in most strong
coupling system, the data can't be cached due to the access pattern and moreover the first accessed data which are
usually frequently accessed are not cached, as a result, system performance is heavily degraded. In this paper, we
propose the new storage system called saving energy RAID (SERAID), in which we place the frequently accessed data
into solid state disks (SSD) and place the less frequently accessed ones into conventional hard disks (CHD). Because the
energy consumption is very low and the random read/write rate is very fast in SSD, we can get high availability and high
saving energy RAID system at the expense of very few costs. The simulation result shows that the random write performance
of SERAID is 10 times rapid than those of traditional RAID and the random read performance of SERAID is
5 times rapid than those of conventional RAID. Besides that, the mean energy consumption of SERAIDsystem is lower
than that of traditional RAID.
In the recent past, wireless sensor networks have found their way into a wide variety of applications and systems with
vastly varying requirements and characteristics. The major limit to the sensor nodes is the limit of energy and computing
capability. The major consumption of the nodes energy in sensor networks occurs in the communication between nodes
or between the nodes and the base station. Many current protocols only pay attention to how to reduce the energy
consumption, rather than the stability during the routing process. Aimed to solve this problem, the paper produces a new
kind of reliable and energy-efficient wave routing algorithm. The results of the experimentation can indicate that this new
algorithm can not only reduce the energy consumption, but also ensure the stability of the routing.
Volume holographic storage (VHS) is currently the subject of widespread interest as a fast-readout-rate, high-capacity
digital data-storage technology. To make need of characteristics of the VHS, the paper present the file system using a
virtual storage layer (VSL) which can be compatible with the logic layer of the current used file system and
accommodate the requirement of VHS in the physical layer. The VSL which is made of the super block, directory area,
the metadata area and dynamic file area can connect directly to the storage media one side and implement compatible to
the existing file system by providing the operating interfaces for the above logical file system. We produce the two layer
storage structure which effectively reduces the number of disk accessed and improves the speed of file read and write.
The allocation mode of 'hybrid of block and zone' and allocation strategy of 'block priority' greatly improve the space
utilization rate of storage device and enforce the storage adaptability in VHS.
This paper presents a novel storage architecture called Volume Holographic Universal Storage Cache (for short VHUSC) for the purpose of optimizing disk I/O performance. The main idea of VHUSC is to make use of the Volume Holographic Memory, referred to as VHUSC, as a new layer between main memory and disk. VHUSC can lower the disk access latency, provide much higher I/O bandwidth and throughput. An application independent model based on queuing theory is proposed for performance comparison between VHUSC and traditional disk. The results show performance improvements of up to one order of magnitude.
The Volume Holographic Data Storage (VHDS) is an optical technology that allows one million bits of data to be written and read out in single flashes of light. To accommodate the characteristics of VHDS, this paper presents the following strategies in designing the file system based on VHDS: (1) Construct the virtual storage layer on the Holographic Storage media, which turns the storage-on-pages into the storage-on-blocks. (2) Use the two-layer structure of the directory table and the index node, and the data stored in the immediate area of the index node. This method can access the index node and the content (partial or all) of the file with an accessing operation. (3) Adopt the allocating method of the page priority in storing data--allocate the whole page to a file while the length of the file exceeds the page. In the meantime, a page is partitioned into many zones to enhance the storing utilities of VHDS. (4) To meet the three-dimension storage's need, the two-dimension Logical Block Address (LBA) is to be used, and makes the more continuity between data blocks--allocate the continuous data blocks in vertical and horizontal direction while storing data. The simulation test shows that the file system can be compatible with the existing file system, and has better stability.
The Gigabit Ethernet technology has already been maturity. Compared with other technology, Gigabit Ethernet technology possesses higher performance and more convenience realization, so in volume holographic storage (VHM) system, we choose Gigabit Ethernet as channel interface of volume holographic storage.
KEYWORDS: Data storage, Network security, Computing systems, Chemical elements, Network architectures, Switches, Data storage servers, Fiber characterization, Computer security, Control systems
The steady and fast increase of data intensive application is violently driving the demand for more data storage capacity and new storage architecture. The server-attached storage approach is being replaced by storage area networks (SANs), whose primary purpose is the transfer of data between computer systems and storage elements or among storage elements, allowing storage devices to be shared among multiple servers. In this paper, we mainly analyze the different characters of Fibre Channel, iSCSI and InfiniBand used within the SANs environment. This paper discusses the issues of protocol performance, protocol scalability, the security mechanism, the interoperability and adaptability with SAN environments, the cost of investment of each architecture and so on. Comparing the performance of traditional direct attached storage, the findings show that all Fibre Channel, InfiniBand and iSCSI are the competent gigabit networking technology for storage area networks. Each protocol has its own advantages and disadvantages. Due to the overwhelming benefits of economy, covenience and high performance/cost ratio, more enterprise can deploy iSCSI SAN based on mature and existing TCP/IP infrastructure.
KEYWORDS: Remote sensing, Volume holography, Holography, Very large scale integration, Data storage, Data processing, Digital holography, Field programmable gate arrays, Modulation, Scattering
Volume holography is currently the subject of widespread interest as a fast-readout-rate, high-capacity digital data-storage technology. However, due to the effect of cross-talk noise, scattering noise, noise gratings formed during a multiple exposure schedule, it brings a lot of burst errors and random errors in the system. Reed-Solomon error-correction codes have been widely used to protect digital data against errors. This paper presents VLSI implementations of an 16 errors correcting (255,223) Reed-Solomon decoder architecture for volume holographic storage. We describe the Reed-Solomon decoders using modified Euclidean algorithms which are regular and simple, and naturally suitable for VLSI implementations. We design the speedily multiplication for GF(28) and pipeline structure to solve hardware complexity and high data processing rate for the Reed-Solomon decoders. We adopt high speed FPGA and have a data processing rate of 200 Mbit/s.
A new image segmenting method with multi-agent structure is proposed to cope with the image variability and the intrinsic complexity of segmenting tasks. This method includes agents of nine different functions, namely, control, multi-valued segmentation, region splitting, region merging, marking, regional feature calculation, spatial relationship analysis, and confidence calculation. With the exception of carrying on communication in the form of instructions and answers, the communication and coordination of work between agents are performed through the reception and operation of various (original and processing-generated) data on the blackboard. The final segmentation results jointly obtained by the multiple agents take segmented subregion confidence as a component for characterizing the region feature vector. The object identification algorithm will make use of the domain knowledge of objects and features with confidence component for detection and identification of the segmentation results. The flexibility, adaptability and robustness of this method have been confirmed by experimental results.
General algorithms of contour tracing are just for binary image, and fail in some complicated images. These algorithms are correct just in some ordinary cases. The reasons of failing are always the lack of theory and the pixel is not enough for contour tracing. The theory of crack brought by A.Rosenfeld is very useful for contour tracing. But the crack is not intuitionistic. So, a new pixel-based algorithm of contour tracing for multi-value segmented image is presented by using the character of crack. After analyzing all cases that maybe occur in contour tracing, this paper summarized a succinct theory. As we know, the contours maybe superpose and intersect, so the same pixel maybe occurs several times in contour tracing, but the corresponding crack is unique, if we find the crack, then the corresponding pixel is found. That is the idea of the paper. The new algorithm is easy and accurate compared the traditional algorithms. In addition, this paper analyzed all relations that maybe occur between regions, pointed a effective algorithm of analyzing the inclusion relations among the regions to build the tree structure. The former algorithms fail in analyzing the tree structure of multi-value segmented image, but the algorithm is effective in all case. Experiments show that these algorithms are correct and high-effective.
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