Use of Information Systems for Data Storage

Статья рассказывает о развивающихся надежных технологиях хранения данных и информационных ресурсов, доступа к ним через сеть, а также о не менее важном аспекте – резервном копировании

EU DataGRID testbed management and support at CERN

In this paper we report on the first two years of running the CERN testbed site for the EU DataGRID project. The site consists of about 120 dual-processor PCs distributed over several testbeds used for different purposes: software development, system integration, and application tests. Activities at the site included test productions of MonteCarlo data for LHC experiments, tutorials and demonstrations of GRID technologies, and support for individual users analysis. This paper focuses on node installation and configuration techniques, service management, user support in a gridified environment, and includes considerations on scalability and security issues and comparisons with "traditional" production systems, as seen from the administrator point of view.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX. PSN THCT00

An Efficient Storage Mechanism to Distribute Disk Load in a VoD Server

In this paper, a storage mechanism is devised to balance the load and to provide immediate service to the clients with a start-up delay of 2ms to 7 ms. The video storage is based on the probability of the clients requesting for the video. Videos with higher probability of being requested are stored and replicated to ensure guaranteed retrieval. Parity generation scheme is employed to provide reliability to non-popular videos. The system is also capable of handling disk failures transparently and thereby providing a reliable service to the clients

Tools for modelling and simulating migration-based preservation

This report describes two tools for modelling and simulating the costs and risks of using IT storage systems for the long-term archiving of file-based AV assets. The tools include a model of storage costs, the ingest and access of files, the possibility of data corruption and loss from a range of mechanisms, and the impact of having limited resources with which to fulfill access requests and preservation actions. Applications include archive planning, development of a technology strategy, cost estimation for business planning, operational decision support, staff training and generally promoting awareness of the issues and challenges archives face in digital preservation

CRAID: Online RAID upgrades using dynamic hot data reorganization

Current algorithms used to upgrade RAID arrays typically require large amounts of data to be migrated, even those that move only the minimum amount of data required to keep a balanced data load. This paper presents CRAID, a self-optimizing RAID array that performs an online block reorganization of frequently used, long-term accessed data in order to reduce this migration even further. To achieve this objective, CRAID tracks frequently used, long-term data blocks and copies them to a dedicated partition spread across all the disks in the array. When new disks are added, CRAID only needs to extend this process to the new devices to redistribute this partition, thus greatly reducing the overhead of the upgrade process. In addition, the reorganized access patterns within this partition improve the array’s performance, amortizing the copy overhead and allowing CRAID to offer a performance competitive with traditional RAIDs. We describe CRAID’s motivation and design and we evaluate it by replaying seven real-world workloads including a file server, a web server and a user share. Our experiments show that CRAID can successfully detect hot data variations and begin using new disks as soon as they are added to the array. Also, the usage of a dedicated partition improves the sequentiality of relevant data access, which amortizes the cost of reorganizations. Finally, we prove that a full-HDD CRAID array with a small distributed partition (<1.28% per disk) can compete in performance with an ideally restriped RAID-5 and a hybrid RAID-5 with a small SSD cache.Peer ReviewedPostprint (published version