Search results for "Operating system"
showing 10 items of 134 documents
FADaC
2019
Solid state drives (SSDs) implement a log-structured write pattern, where obsolete data remains stored on flash pages until the flash translation layer (FTL) erases them. erase() operations, however, cannot erase a single page, but target entire flash blocks. Since these victim blocks typically store a mix of valid and obsolete pages, FTLs have to copy the valid data to a new block before issuing an erase() operation. This process therefore increases the latencies of concurrent I/Os and reduces the lifetime of flash memory. Data classification schemes identify data pages with similar update frequencies and group them together. FTLs can use this grouping to design garbage collection strategi…
Hypervisor memory acquisition for ARM
2021
Abstract Cyber forensics use memory acquisition in advanced forensics and malware analysis. We propose a hypervisor based memory acquisition tool. Our implementation extends the volatility memory forensics framework by reducing the processor's consumption, solves the in-coherency problem in the memory snapshots and mitigates the pressure of the acquisition on the network and the disk. We provide benchmarks and evaluation.
Extending SSD lifetime in database applications with page overwrites
2013
Flash-based Solid State Disks (SSDs) have been a great success story over the last years and are widely used in embedded systems, servers, and laptops.One often overlooked ability of NAND flash is that flash pages can be overwritten in certain circumstances. This can be used to decrease wear out and increase performance.In this paper, we analyze the potential of overwrites for the most used data structure in database applications: the B-Tree. We show that with overwrites it is possible to significantly reduce flash wear out and increase overall performance.
CORAL Server and CORAL Server Proxy: Scalable Access to Relational Databases from CORAL Applications
2011
The CORAL software is widely used at CERN for accessing the data stored by the LHC experiments using relational database technologies. CORAL provides a C++ abstraction layer that supports data persistency for several backends and deployment models, including local access to SQLite files, direct client access to Oracle and MySQL servers, and read-only access to Oracle through the FroNTier web server and cache. Two new components have recently been added to CORAL to implement a model involving a middle tier "CORAL server" deployed close to the database and a tree of "CORAL server proxy" instances, with data caching and multiplexing functionalities, deployed close to the client. The new compon…
CORAL and COOL during the LHC long shutdown.
2013
CORAL and COOL are two software packages used by the LHC experiments for managing detector conditions and other types of data using relational database technologies. They have been developed and maintained within the LCG Persistency Framework, a common project of the CERN IT department with ATLAS, CMS and LHCb. This presentation reports on the status of CORAL and COOL at the time of CHEP2013, covering the new features and enhancements in both packages, as well as the changes and improvements in the software process infrastructure. It also reviews the usage of the software in the experiments and the outlook for ongoing and future activities during the LHC long shutdown (LS1) and beyond. CORA…
GekkoFS — A Temporary Burst Buffer File System for HPC Applications
2020
Many scientific fields increasingly use high-performance computing (HPC) to process and analyze massive amounts of experimental data while storage systems in today’s HPC environments have to cope with new access patterns. These patterns include many metadata operations, small I/O requests, or randomized file I/O, while general-purpose parallel file systems have been optimized for sequential shared access to large files. Burst buffer file systems create a separate file system that applications can use to store temporary data. They aggregate node-local storage available within the compute nodes or use dedicated SSD clusters and offer a peak bandwidth higher than that of the backend parallel f…
Job seeker's spatial equilibrium in a fuzzy mathematical framework
1990
This paper incorporates complex behavior in a job seeking strategy model. Since the state of information is imperfect, a job seeker faces an imprecise labor market. His behavior is fuzzy and variable. It is shown how this complex behavior can be described by fuzzy subsets theory and bifurcation analysis. The latter examines the discontinuous phenomena. Then it is proved that a job seeker’s fuzzy equilibrium with a spatial constraint exists.
Virtual Vehicles Manager: a java virtual reality environment for distributed multi vehicles dynamics control and simulation
2007
This paper describes a lightweight, full portable software environment for development, simulation and control of vehicles. All the software is developed in Java so there are many advantages as portability, multithreading distribution etc. This environment simulates the vehicles integrating their non-linear differential equation systems. The equation systems can easily be modified changing that representation class so it is easy to manage different vehicles. The scenario is displayed as a 3D virtual reality environment in which all the objects are rendered using a combination of 3 d primitive. It is also possible the use of pre-built 3 d objects loaded from files in 3 ds format. The softwar…
iTeXMac: An Integrated TeX Environment for Mac OS X
2004
iTeXMac is an integrated suite of three major components: a text editor detailed in section 2, a PDF viewer detailed in section 3, and a TeX front end detailed in section 4. Some notes on installation are followed by remarks concerning inter-application communication in section 6 for other Mac OS X developers. Finally, the pdfsync feature and the TeX Wrapper are discussed in sections 7 and 8. Since they concern the synchronization between the TeX source and PDF output, and a definition for a shared TeX document structure, both will certainly interest the whole TeX community.
Impulsive control on the synchronization for a class of chaotic Systems
2014
In this paper, the impulsive control problem on the synchronization for a class of chaotic systems is discussed. Based on Lyapunov stability theory, the new impulsive synchronization strategy is presented to realize the chaos synchronization and possesses the wider scope of application. Finally the numerical simulation examples are given to demonstrate the effectiveness of our theoretical results.