File Systems and Disk Layout I/O: the Big Picture
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Copy on Write Based File Systems Performance Analysis and Implementation
Copy On Write Based File Systems Performance Analysis And Implementation Sakis Kasampalis Kongens Lyngby 2010 IMM-MSC-2010-63 Technical University of Denmark Department Of Informatics Building 321, DK-2800 Kongens Lyngby, Denmark Phone +45 45253351, Fax +45 45882673 [email protected] www.imm.dtu.dk Abstract In this work I am focusing on Copy On Write based file systems. Copy On Write is used on modern file systems for providing (1) metadata and data consistency using transactional semantics, (2) cheap and instant backups using snapshots and clones. This thesis is divided into two main parts. The first part focuses on the design and performance of Copy On Write based file systems. Recent efforts aiming at creating a Copy On Write based file system are ZFS, Btrfs, ext3cow, Hammer, and LLFS. My work focuses only on ZFS and Btrfs, since they support the most advanced features. The main goals of ZFS and Btrfs are to offer a scalable, fault tolerant, and easy to administrate file system. I evaluate the performance and scalability of ZFS and Btrfs. The evaluation includes studying their design and testing their performance and scalability against a set of recommended file system benchmarks. Most computers are already based on multi-core and multiple processor architec- tures. Because of that, the need for using concurrent programming models has increased. Transactions can be very helpful for supporting concurrent program- ming models, which ensure that system updates are consistent. Unfortunately, the majority of operating systems and file systems either do not support trans- actions at all, or they simply do not expose them to the users. -
The Linux Kernel Module Programming Guide
The Linux Kernel Module Programming Guide Peter Jay Salzman Michael Burian Ori Pomerantz Copyright © 2001 Peter Jay Salzman 2007−05−18 ver 2.6.4 The Linux Kernel Module Programming Guide is a free book; you may reproduce and/or modify it under the terms of the Open Software License, version 1.1. You can obtain a copy of this license at http://opensource.org/licenses/osl.php. This book is distributed in the hope it will be useful, but without any warranty, without even the implied warranty of merchantability or fitness for a particular purpose. The author encourages wide distribution of this book for personal or commercial use, provided the above copyright notice remains intact and the method adheres to the provisions of the Open Software License. In summary, you may copy and distribute this book free of charge or for a profit. No explicit permission is required from the author for reproduction of this book in any medium, physical or electronic. Derivative works and translations of this document must be placed under the Open Software License, and the original copyright notice must remain intact. If you have contributed new material to this book, you must make the material and source code available for your revisions. Please make revisions and updates available directly to the document maintainer, Peter Jay Salzman <[email protected]>. This will allow for the merging of updates and provide consistent revisions to the Linux community. If you publish or distribute this book commercially, donations, royalties, and/or printed copies are greatly appreciated by the author and the Linux Documentation Project (LDP). -
Devicelock® DLP 8.3 User Manual
DeviceLock® DLP 8.3 User Manual © 1996-2020 DeviceLock, Inc. All Rights Reserved. Information in this document is subject to change without notice. No part of this document may be reproduced or transmitted in any form or by any means for any purpose other than the purchaser’s personal use without the prior written permission of DeviceLock, Inc. Trademarks DeviceLock and the DeviceLock logo are registered trademarks of DeviceLock, Inc. All other product names, service marks, and trademarks mentioned herein are trademarks of their respective owners. DeviceLock DLP - User Manual Software version: 8.3 Updated: March 2020 Contents About This Manual . .8 Conventions . 8 DeviceLock Overview . .9 General Information . 9 Managed Access Control . 13 DeviceLock Service for Mac . 17 DeviceLock Content Security Server . 18 How Search Server Works . 18 ContentLock and NetworkLock . 20 ContentLock and NetworkLock Licensing . 24 Basic Security Rules . 25 Installing DeviceLock . .26 System Requirements . 26 Deploying DeviceLock Service for Windows . 30 Interactive Installation . 30 Unattended Installation . 35 Installation via Microsoft Systems Management Server . 36 Installation via DeviceLock Management Console . 36 Installation via DeviceLock Enterprise Manager . 37 Installation via Group Policy . 38 Installation via DeviceLock Enterprise Server . 44 Deploying DeviceLock Service for Mac . 45 Interactive Installation . 45 Command Line Utility . 47 Unattended Installation . 48 Installing Management Consoles . 49 Installing DeviceLock Enterprise Server . 52 Installation Steps . 52 Installing and Accessing DeviceLock WebConsole . 65 Prepare for Installation . 65 Install the DeviceLock WebConsole . 66 Access the DeviceLock WebConsole . 67 Installing DeviceLock Content Security Server . 68 Prepare to Install . 68 Start Installation . 70 Perform Configuration and Complete Installation . 71 DeviceLock Consoles and Tools . -
Semiconductor Memories
Semiconductor Memories Prof. MacDonald Types of Memories! l" Volatile Memories –" require power supply to retain information –" dynamic memories l" use charge to store information and require refreshing –" static memories l" use feedback (latch) to store information – no refresh required l" Non-Volatile Memories –" ROM (Mask) –" EEPROM –" FLASH – NAND or NOR –" MRAM Memory Hierarchy! 100pS RF 100’s of bytes L1 1nS SRAM 10’s of Kbytes 10nS L2 100’s of Kbytes SRAM L3 100’s of 100nS DRAM Mbytes 1us Disks / Flash Gbytes Memory Hierarchy! l" Large memories are slow l" Fast memories are small l" Memory hierarchy gives us illusion of large memory space with speed of small memory. –" temporal locality –" spatial locality Register Files ! l" Fastest and most robust memory array l" Largest bit cell size l" Basically an array of large latches l" No sense amps – bits provide full rail data out l" Often multi-ported (i.e. 8 read ports, 2 write ports) l" Often used with ALUs in the CPU as source/destination l" Typically less than 10,000 bits –" 32 32-bit fixed point registers –" 32 60-bit floating point registers SRAM! l" Same process as logic so often combined on one die l" Smaller bit cell than register file – more dense but slower l" Uses sense amp to detect small bit cell output l" Fastest for reads and writes after register file l" Large per bit area costs –" six transistors (single port), eight transistors (dual port) l" L1 and L2 Cache on CPU is always SRAM l" On-chip Buffers – (Ethernet buffer, LCD buffer) l" Typical sizes 16k by 32 Static Memory -
The Linux Device File-System
The Linux Device File-System Richard Gooch EMC Corporation [email protected] Abstract 1 Introduction All Unix systems provide access to hardware via de- vice drivers. These drivers need to provide entry points for user-space applications and system tools to access the hardware. Following the \everything is a file” philosophy of Unix, these entry points are ex- posed in the file name-space, and are called \device The Device File-System (devfs) provides a power- special files” or \device nodes". ful new device management mechanism for Linux. Unlike other existing and proposed device manage- This paper discusses how these device nodes are cre- ment schemes, it is powerful, flexible, scalable and ated and managed in conventional Unix systems and efficient. the limitations this scheme imposes. An alternative mechanism is then presented. It is an alternative to conventional disc-based char- acter and block special devices. Kernel device drivers can register devices by name rather than de- vice numbers, and these device entries will appear in the file-system automatically. 1.1 Device numbers Devfs provides an immediate benefit to system ad- ministrators, as it implements a device naming scheme which is more convenient for large systems Conventional Unix systems have the concept of a (providing a topology-based name-space) and small \device number". Each instance of a driver and systems (via a device-class based name-space) alike. hardware component is assigned a unique device number. Within the kernel, this device number is Device driver authors can benefit from devfs by used to refer to the hardware and driver instance. -
High Velocity Kernel File Systems with Bento
High Velocity Kernel File Systems with Bento Samantha Miller, Kaiyuan Zhang, Mengqi Chen, and Ryan Jennings, University of Washington; Ang Chen, Rice University; Danyang Zhuo, Duke University; Thomas Anderson, University of Washington https://www.usenix.org/conference/fast21/presentation/miller This paper is included in the Proceedings of the 19th USENIX Conference on File and Storage Technologies. February 23–25, 2021 978-1-939133-20-5 Open access to the Proceedings of the 19th USENIX Conference on File and Storage Technologies is sponsored by USENIX. High Velocity Kernel File Systems with Bento Samantha Miller Kaiyuan Zhang Mengqi Chen Ryan Jennings Ang Chen‡ Danyang Zhuo† Thomas Anderson University of Washington †Duke University ‡Rice University Abstract kernel-level debuggers and kernel testing frameworks makes this worse. The restricted and different kernel programming High development velocity is critical for modern systems. environment also limits the number of trained developers. This is especially true for Linux file systems which are seeing Finally, upgrading a kernel module requires either rebooting increased pressure from new storage devices and new demands the machine or restarting the relevant module, either way on storage systems. However, high velocity Linux kernel rendering the machine unavailable during the upgrade. In the development is challenging due to the ease of introducing cloud setting, this forces kernel upgrades to be batched to meet bugs, the difficulty of testing and debugging, and the lack of cloud-level availability goals. support for redeployment without service disruption. Existing Slow development cycles are a particular problem for file approaches to high-velocity development of file systems for systems. -
Deviceinstaller User Guide
Device Installer User Guide Part Number 900-325 Revision C 03/18 Table of Contents 1. Overview ...................................................................................................................................... 1 2. Devices ........................................................................................................................................ 2 Choose the Network Adapter for Communication ....................................................................... 2 Search for All Devices on the Network ........................................................................................ 2 Change Views .............................................................................................................................. 2 Add a Device to the List ............................................................................................................... 3 View Device Details ..................................................................................................................... 3 Device Lists ................................................................................................................................. 3 Save the Device List ................................................................................................................ 3 Open the Device List ............................................................................................................... 4 Print the Device List ................................................................................................................ -
Oracle® Linux 7 Managing File Systems
Oracle® Linux 7 Managing File Systems F32760-07 August 2021 Oracle Legal Notices Copyright © 2020, 2021, Oracle and/or its affiliates. This software and related documentation are provided under a license agreement containing restrictions on use and disclosure and are protected by intellectual property laws. Except as expressly permitted in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast, modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for interoperability, is prohibited. The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing. If this is software or related documentation that is delivered to the U.S. Government or anyone licensing it on behalf of the U.S. Government, then the following notice is applicable: U.S. GOVERNMENT END USERS: Oracle programs (including any operating system, integrated software, any programs embedded, installed or activated on delivered hardware, and modifications of such programs) and Oracle computer documentation or other Oracle data delivered to or accessed by U.S. Government end users are "commercial computer software" or "commercial computer software documentation" pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. As such, the use, reproduction, duplication, release, display, disclosure, modification, preparation of derivative works, and/or adaptation of i) Oracle programs (including any operating system, integrated software, any programs embedded, installed or activated on delivered hardware, and modifications of such programs), ii) Oracle computer documentation and/or iii) other Oracle data, is subject to the rights and limitations specified in the license contained in the applicable contract. -
Linux Cdrom Documentation
Linux Cdrom Documentation The kernel development community Jul 14, 2020 CONTENTS i ii CHAPTER ONE A LINUX CD-ROM STANDARD Author David van Leeuwen <[email protected]> Date 12 March 1999 Updated by Erik Andersen ([email protected]) Updated by Jens Axboe ([email protected]) 1.1 Introduction Linux is probably the Unix-like operating system that supports the widest variety of hardware devices. The reasons for this are presumably • The large list of hardware devices available for the many platforms that Linux now supports (i.e., i386-PCs, Sparc Suns, etc.) • The open design of the operating system, such that anybody can write a driver for Linux. • There is plenty of source code around as examples of how to write a driver. The openness of Linux, and the many different types of available hardware has al- lowed Linux to support many different hardware devices. Unfortunately, the very openness that has allowed Linux to support all these different devices has also allowed the behavior of each device driver to differ significantly from one device to another. This divergence of behavior has been very significant for CD-ROM devices; the way a particular drive reacts to a standard ioctl() call varies greatly from one device driver to another. To avoid making their drivers totally inconsis- tent, the writers of Linux CD-ROM drivers generally created new device drivers by understanding, copying, and then changing an existing one. Unfortunately, this practice did not maintain uniform behavior across all the Linux CD-ROM drivers. This document describes an effort to establish Uniform behavior across all the dif- ferent CD-ROM device drivers for Linux. -
Managing File Systems in Oracle® Solaris 11.4
® Managing File Systems in Oracle Solaris 11.4 Part No: E61016 November 2020 Managing File Systems in Oracle Solaris 11.4 Part No: E61016 Copyright © 2004, 2020, Oracle and/or its affiliates. License Restrictions Warranty/Consequential Damages Disclaimer This software and related documentation are provided under a license agreement containing restrictions on use and disclosure and are protected by intellectual property laws. Except as expressly permitted in your license agreement or allowed by law, you may not use, copy, reproduce, translate, broadcast, modify, license, transmit, distribute, exhibit, perform, publish, or display any part, in any form, or by any means. Reverse engineering, disassembly, or decompilation of this software, unless required by law for interoperability, is prohibited. Warranty Disclaimer The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing. Restricted Rights Notice If this is software or related documentation that is delivered to the U.S. Government or anyone licensing it on behalf of the U.S. Government, then the following notice is applicable: U.S. GOVERNMENT END USERS: Oracle programs (including any operating system, integrated software, any programs embedded, installed or activated on delivered hardware, and modifications of such programs) and Oracle computer documentation or other Oracle data delivered to or accessed by U.S. Government end users are "commercial computer software" or "commercial -
EEPROM Emulation
...the world's most energy friendly microcontrollers EEPROM Emulation AN0019 - Application Note Introduction This application note demonstrates a way to use the flash memory of the EFM32 to emulate single variable rewritable EEPROM memory through software. The example API provided enables reading and writing of single variables to non-volatile flash memory. The erase-rewrite algorithm distributes page erases and thereby doing wear leveling. This application note includes: • This PDF document • Source files (zip) • Example C-code • Multiple IDE projects 2013-09-16 - an0019_Rev1.09 1 www.silabs.com ...the world's most energy friendly microcontrollers 1 General Theory 1.1 EEPROM and Flash Based Memory EEPROM stands for Electrically Erasable Programmable Read-Only Memory and is a type of non- volatile memory that is byte erasable and therefore often used to store small amounts of data that must be saved when power is removed. The EFM32 microcontrollers do not include an embedded EEPROM module for byte erasable non-volatile storage, but all EFM32s do provide flash memory for non-volatile data storage. The main difference between flash memory and EEPROM is the erasable unit size. Flash memory is block-erasable which means that bytes cannot be erased individually, instead a block consisting of several bytes need to be erased at the same time. Through software however, it is possible to emulate individually erasable rewritable byte memory using block-erasable flash memory. To provide EEPROM functionality for the EFM32s in an application, there are at least two options available. The first one is to include an external EEPROM module when designing the hardware layout of the application. -
A Hybrid Swapping Scheme Based on Per-Process Reclaim for Performance Improvement of Android Smartphones (August 2018)
Received August 19, 2018, accepted September 14, 2018, date of publication October 1, 2018, date of current version October 25, 2018. Digital Object Identifier 10.1109/ACCESS.2018.2872794 A Hybrid Swapping Scheme Based On Per-Process Reclaim for Performance Improvement of Android Smartphones (August 2018) JUNYEONG HAN 1, SUNGEUN KIM1, SUNGYOUNG LEE1, JAEHWAN LEE2, AND SUNG JO KIM2 1LG Electronics, Seoul 07336, South Korea 2School of Software, Chung-Ang University, Seoul 06974, South Korea Corresponding author: Sung Jo Kim ([email protected]) This work was supported in part by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education under Grant 2016R1D1A1B03931004 and in part by the Chung-Ang University Research Scholarship Grants in 2015. ABSTRACT As a way to increase the actual main memory capacity of Android smartphones, most of them make use of zRAM swapping, but it has limitation in increasing its capacity since it utilizes main memory. Unfortunately, they cannot use secondary storage as a swap space due to the long response time and wear-out problem. In this paper, we propose a hybrid swapping scheme based on per-process reclaim that supports both secondary-storage swapping and zRAM swapping. It attempts to swap out all the pages in the working set of a process to a zRAM swap space rather than killing the process selected by a low-memory killer, and to swap out the least recently used pages into a secondary storage swap space. The main reason being is that frequently swap- in/out pages use the zRAM swap space while less frequently swap-in/out pages use the secondary storage swap space, in order to reduce the page operation cost.