Highly scalable metadata distribution algorithm in mass storage system

Distribution of metadata in a metadata server cluster is important in mass storage system. A good distribution algorithm has a significant influence on the system performance, availability and scalability. Subtree partition and hash are two traditional metadata distribution algorithms used in distributed file systems. They both have a defect in system scalability. This paper proposes a new directory hash （DH） algorithm. By treating directory as the key value of hash function, implementing concentrated storage of metadata, pipelining operations and prefetching technology, DH algorithm can enhance the system scalability on the premise without sacrificing system performance.

Security System in United Storage Network and Its Implementation

With development of networked storage and its applications, united storage network (USN) combined with network attached storage (NAS) and storage area network (SAN) has emerged. It has such advantages as high performance, low cost, good connectivity, etc. However the security issue has been complicated because USN responds to block I/O and file I/O requests simultaneously. In this paper, a security system module is developed to prevent many types of attacks against USN based on NAS head. The module not only uses effective authentication to prevent unauthorized access to the system data, but also checks the data integrity. Experimental results show that the security module can not only resist remote attacks and attacks from those who has physical access to the USN, but can also be seamlessly integrated into underlying file systems, with little influence on their performance.

Research on the Security of the United Storage Network Based on NAS

A multi-user view file system (MUVFS) and a security scheme are developed to improve the security of the united storage network (USN) that integrates a network attached storage (NAS) and a storage area network (SAN). The MUVFS offers a storage volume view for each authorized user who can access only the data in his own storage volume, the security scheme enables all users to encrypt and decrypt the data of their own storage view at client-side, and the USN server needs only to check the users’ identities and the data’s integrity. Experiments were performed to compare the sequential read, write and read/write rates of NFS+MUVFS+secure_module with those of NFS. The results indicate that the security of the USN is improved greatly with little influence on the system performance when the MUVFS and the security scheme are integrated into it.

A Measuring Solution for Mechanical Characteristics of MO Disks

Mechanical characteristics of MO disk are vital for the designer of the drives and the manufacturers who provide the mass-product MO disks. So measuring mechanical characteristics is very significant. We compares the existing measuring methods and gives some novel measuring methods we adopted in details. The measuring system based upon these methods was introduced too. Some typical measuring results are also shown in this paper.

基于块的逻辑层次集群:一种分布式多媒体点播服务器的体系结构(英文)

A structure of logical hierarchical cluster for the distributed multimedia on demand server is proposed. The architecture is mainly composed of the network topology and the resource management of all server nodes. Instead of the physical network hierarchy or the independent management hierarchy, the nodes are organized into a logically hieraxchical cluster according to the multimedia block they caches in the midderware layer. The process of a member joining/leaving or the structure adjustment cooperatively implemented by all members is concerned with decentralized maintenance of the logical cluster hierarchy. As the root of each logically hierarchical cluster is randomly mapped into the system, the logical structure of a multimedia block is dynamically expanded across some regions by the two replication policies in different load state respectively. The local load diversion is applied to fine-tune the load of nodes within a local region but belongs to different logical hierarchies. Guaranteed by the dynamic expansion of a logical structure and the load diversion of a local region, the users always select a closest idle node from the logical hierarchy under the condition of topology integration with resource management.

On the Behavior Characteristics of Cellular Automata

In this paper, the inherent rdationships between the running regulations and behavior charactcristics of cellular automata are presented; an imprecise taxonomy of such syseros is put forward; the three extreme cases of slablc sysems are discussed; and the illogicalness of evolutional strategies of cellular automata is analyzed. The result is suilable for the emulation and prediction of behavior of discrete dynamics sys terns; especially it can be taken as an important analysis means of dynamic performance of complex networks.

Improved Disk Scheduling Algorithms Based on Rotational Position

As increase of disk access speed has far lagged the speed of processors and main memory, disk-scheduling performance, although less significant for personal users with dedicated storage, is crucial for internet-based intensive data processing. For modern disks, increase of disk rotation rate makes overhead of disk access to data transfer heavier. Therefore, it seems more important to improve both parallel processing capability of disk I/O and disk-scheduling performance at the same time. For disk-scheduling algorithms based on both disk arm and rotational positions, their time-resolving powers are more precise in comparison with those for disk-scheduling algorithms based only on disk arm position. Algorithms of this sort are studied in this paper. Several improved algorithms based on rotational position are proposed, and simulation results of their performances demonstrate.

Color and neighbor edge directional difference feature for image retrieval

A novel image feature termed neighbor edge directional difference unit histogram is proposed, in which the neighbor edge directional difference unit is defined and computed for every pixel in the image, and is used to generate the neighbor edge directional difference unit histogram. This histogram and color histogram are used as feature indexes to retrieve color image. The feature is invariant to image scaling and translation and has more powerful descriptive for the natural color images. Experimental results show that the feature can achieve better retrieval performance than other color-spatial features.

Analog Module Placement Design Using Genetic Algorithm

This paper presents a novel genetic algorithm for analog module placement based on a generalization of the two-dimensional bin packing problem. The genetic encoding and operators assure that all problem constraints are always satisfied. Thus the potential problems of adding penalty terms to the cost function are eliminated so that the search configuration space is drastically decreased. The dedicated cost function is based on the special requirements of analog integrated circuits. A fractional factorial experiment was conducted using an orthogonal array to study the algorithm parameters. A meta-GA was applied to determine the optimal parameter values. The algorithm was tested with several local benchmark circuits. The experimental results show that the algorithm has better performance than the simulated annealing approach with satisfactory results comparable to manual placement. This study demonstrates the effectiveness of the genetic algorithm in the analog module placement problem. The algorithm has been successfully used in a layout synthesis tool.