Showing papers on "Data Corruption published in 2005"

System and method to prevent data corruption due to split brain in shared data clusters

Abstract: A system and to prevent data corruption due to split brain in shared data clusters includes two or more nodes of a cluster, a shared storage device, and an update manager. The update manager may be configured to maintain a local persistent store corresponding to each node of the cluster. On receiving an update request directed to the shared storage device from a first node, the update manager may be configured to redirect the update to the local persistent store corresponding to the first node. The update manager may be further configured to verify a cluster membership status of the first node, and to transfer the contents of the update from the local persistent store to the shared storage device if the cluster membership verification succeeds.

Coverage and the use of cyclic redundancy codes in ultra-dependable systems

Abstract: A cyclic redundancy code (CRC), when used properly, can be an effective and relatively inexpensive method to detect data corruption across communication channels. However, some systems use CRCs in ways that violate common assumptions made in analyzing CRC effectiveness, resulting in an overly optimistic prediction of system dependability. CRCs detect errors with some finite probability, which depends on factors including the strength of the particular code used, the bit-error rate, and the message length being checked. Common assumptions also include a passive network inter-stage, explicit data words, memoryless channels, and random independent symbol errors. In this paper we identify some examples of CRC usage that compromise ultra-dependable system design goals, and recommend alternate ways to improve system dependability via architectural approaches rather than error detection coding approaches.

Transactional storage and workflow routing for medical image objects

Abstract: A Picture Archiving and Communications System (PACS) implements medical image, video, and medical record storage, retrieval and archiving with transactional processing having properties of atomicity, consistency, isolation and durability (ACID). A two-phase commit procedure is used to prevent data corruption. Relational database storage of image objects permits images to be stored in a manner that allows a user to determine the quality and other characteristics of the image.

Method and apparatus for restoring a corrupted data volume

Abstract: Disclosed is a method and apparatus for restoring a corrupted data volume. In one embodiment, the method includes creating a backup copy of the data volume before the data volume is corrupted. Data transactions that modify the contents of the data volume are stored in a transaction log. After detection of the data corruption, a virtual copy of the backup copy is created. Thereafter, select data transactions stored in the transaction log, are applied to the virtual copy. Data of the corrupted data volume is then overwritten with data of the backup copy and data of the virtual copy after applying data transactions to the virtual copy.

Dealing with data corruption in remote sensing

Abstract: Remote sensing has resulted in repositories of data that grow at a pace much faster than can be readily analyzed. One of the obstacles in dealing with remotely sensed data and others is the variable quality of the data. Instrument failures can result in entire missing observation cycles, while cloud cover frequently results in missing or distorted values. We investigated the use of several methods that automatically deal with corruptions in the data. These include robust measures which avoid overfitting, filtering which discards the corrupted instances, and polishing by which the corrupted elements are fitted with more appropriate values. We applied such methods to a data set of vegetation indices and land cover type assembled from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) data collection.

A survey of data protection technologies

Abstract: The most important asset in any computing environment is the data that is being processed. Lost information can be disastrous to any enterprise or corporate. Therefore, data protection is one of the most important tasks performed on any computer systems on a regular basis. The mechanisms used by data protection vary depending on the kind of data to be protected and the type of media used. Traditionally, data protection focuses mainly on backup applications which copies data to removable media that can be shelved and protected. By putting the copy on removable media, they are isolated from the problems that can cause data loss or corruption on the live system. Recent development and cost reduction in hard disk technologies and the growing concern over data safety have made it more attractive to perform data protections using online disk-based media. The author of this paper takes a broader view of data protection and surveys different technologies that are used at different places in a computer system to guard against data loss. Pros and cons of these technologies were analyzed and some best practice guidelines were provided for implementing data protection strategies

Device, method and computer program to avoid data corruption during writing operations

Abstract: A management table includes three pages. A pair of first and second pages is alternately used as a valid page and an invalid page to secure the data. The valid page is copied to a third page. Even when the power is shut off in progress of updating the page, at the next start time, the status of the data writing operation when the power is shut off is determined based on the validity and stability of the pages. Therefore, the data is restored without any corruption of valid page by using a proper restoring method.

Simple modeling of stochastic classical nano-bit data corruption : Probability distribution consideration

Abstract: Motivated by a real-world application of quantum-dot cellular automata (QCA) and with the help of Monte-Carlo simulations and analytic continuum theory, we have studied the corruption or error process of a binary nano-bit model resulting from an interaction with stochastically independent Brownian agents (BAs). Besides, the more specific link to a real-world application, in this work, we have extended the scope of the study and have used the new technique to reproduce results from previous works by Newman and Triampo [Phys. Rev. E 59, 5172 (1999) and Phys. Rev. E 60, 1450 (1999)]. The new findings include 1) the effect of a “patch” or “cluster” of bits on the simulation results, 2) the log-normal vs. normal distribution of the local bit density, and 3) new results for local bit corruption in two dimensions. The theory is compared with the results of simulations, and good agreement is found. The connection of this binary nano-bit model with the real world is discussed, especially in the context of molecular electronics and the quantum-dot cellular automata paradigm. With model extension such as taking into account a more realistic correlation between bits, our hope is that this work may contribute to an understanding of the soft error or the corruption of data stored in nano-scale devices.

Recording and reproducing device, record controlling method, and program

Abstract: PROBLEM TO BE SOLVED: To more surely prevent data corruption caused by recording performance degradation at a low temperature, and also to prevent excessive limitation of a recording operation. SOLUTION: A testing write operation is performed to a storage medium only in accordance with a condition that temperature drops below a prescribed temperature. The permission/nonpermission of a recording operation is determined on the basis of the result. Since a recording operation is not permitted only when recording is actually impossible, the recording operation is not limited excessively. Since recording can be allowed only when recording is actually possible, data corruption is prevented more surely. COPYRIGHT: (C)2006,JPO&NCIPI

Device, method for detecting data corruption, and device, method for restoring data

Abstract: PROBLEM TO BE SOLVED: To detect corruption of data regarding a user, without making the responsiveness lowered, and to protect the data. SOLUTION: A control part decides whether three pieces of data management information agree with each fixed time. Then, the control part decides that "there is no breakdown of data management information" when the three pieces of data management information agree and detects "the breakdown of data management information", when they do not agree. When the corruption of data management information is detected, the broken down data management information is restored by a majority of each piece of data management information. COPYRIGHT: (C)2006,JPO&NCIPI