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Oracle® Linux Administrator's Solutions Guide for Release 6
Oracle® Linux Administrator's Solutions Guide for Release 6 E37355-64 August 2017 Oracle Legal Notices Copyright © 2012, 2017, Oracle and/or its affiliates. All rights reserved. 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 installed on the hardware, and/or documentation, delivered to U.S. Government end users are "commercial computer software" pursuant to the applicable Federal Acquisition Regulation and agency-specific supplemental regulations. As such, use, duplication, disclosure, modification, and adaptation of the programs, including any operating system, integrated software, any programs installed on the hardware, and/or documentation, shall be subject to license terms and license restrictions applicable to the programs. No other rights are granted to the U.S. -
CS 5600 Computer Systems
CS 5600 Computer Systems Lecture 10: File Systems What are We Doing Today? • Last week we talked extensively about hard drives and SSDs – How they work – Performance characterisEcs • This week is all about managing storage – Disks/SSDs offer a blank slate of empty blocks – How do we store files on these devices, and keep track of them? – How do we maintain high performance? – How do we maintain consistency in the face of random crashes? 2 • ParEEons and MounEng • Basics (FAT) • inodes and Blocks (ext) • Block Groups (ext2) • Journaling (ext3) • Extents and B-Trees (ext4) • Log-based File Systems 3 Building the Root File System • One of the first tasks of an OS during bootup is to build the root file system 1. Locate all bootable media – Internal and external hard disks – SSDs – Floppy disks, CDs, DVDs, USB scks 2. Locate all the parEEons on each media – Read MBR(s), extended parEEon tables, etc. 3. Mount one or more parEEons – Makes the file system(s) available for access 4 The Master Boot Record Address Size Descripon Hex Dec. (Bytes) Includes the starEng 0x000 0 Bootstrap code area 446 LBA and length of 0x1BE 446 ParEEon Entry #1 16 the parEEon 0x1CE 462 ParEEon Entry #2 16 0x1DE 478 ParEEon Entry #3 16 0x1EE 494 ParEEon Entry #4 16 0x1FE 510 Magic Number 2 Total: 512 ParEEon 1 ParEEon 2 ParEEon 3 ParEEon 4 MBR (ext3) (swap) (NTFS) (FAT32) Disk 1 ParEEon 1 MBR (NTFS) 5 Disk 2 Extended ParEEons • In some cases, you may want >4 parEEons • Modern OSes support extended parEEons Logical Logical ParEEon 1 ParEEon 2 Ext. -
Ext4 File System and Crash Consistency
1 Ext4 file system and crash consistency Changwoo Min 2 Summary of last lectures • Tools: building, exploring, and debugging Linux kernel • Core kernel infrastructure • Process management & scheduling • Interrupt & interrupt handler • Kernel synchronization • Memory management • Virtual file system • Page cache and page fault 3 Today: ext4 file system and crash consistency • File system in Linux kernel • Design considerations of a file system • History of file system • On-disk structure of Ext4 • File operations • Crash consistency 4 File system in Linux kernel User space application (ex: cp) User-space Syscalls: open, read, write, etc. Kernel-space VFS: Virtual File System Filesystems ext4 FAT32 JFFS2 Block layer Hardware Embedded Hard disk USB drive flash 5 What is a file system fundamentally? int main(int argc, char *argv[]) { int fd; char buffer[4096]; struct stat_buf; DIR *dir; struct dirent *entry; /* 1. Path name -> inode mapping */ fd = open("/home/lkp/hello.c" , O_RDONLY); /* 2. File offset -> disk block address mapping */ pread(fd, buffer, sizeof(buffer), 0); /* 3. File meta data operation */ fstat(fd, &stat_buf); printf("file size = %d\n", stat_buf.st_size); /* 4. Directory operation */ dir = opendir("/home"); entry = readdir(dir); printf("dir = %s\n", entry->d_name); return 0; } 6 Why do we care EXT4 file system? • Most widely-deployed file system • Default file system of major Linux distributions • File system used in Google data center • Default file system of Android kernel • Follows the traditional file system design 7 History of file system design 8 UFS (Unix File System) • The original UNIX file system • Design by Dennis Ritche and Ken Thompson (1974) • The first Linux file system (ext) and Minix FS has a similar layout 9 UFS (Unix File System) • Performance problem of UFS (and the first Linux file system) • Especially, long seek time between an inode and data block 10 FFS (Fast File System) • The file system of BSD UNIX • Designed by Marshall Kirk McKusick, et al. -
Comparing Filesystem Performance: Red Hat Enterprise Linux 6 Vs
COMPARING FILE SYSTEM I/O PERFORMANCE: RED HAT ENTERPRISE LINUX 6 VS. MICROSOFT WINDOWS SERVER 2012 When choosing an operating system platform for your servers, you should know what I/O performance to expect from the operating system and file systems you select. In the Principled Technologies labs, using the IOzone file system benchmark, we compared the I/O performance of two operating systems and file system pairs, Red Hat Enterprise Linux 6 with ext4 and XFS file systems, and Microsoft Windows Server 2012 with NTFS and ReFS file systems. Our testing compared out-of-the-box configurations for each operating system, as well as tuned configurations optimized for better performance, to demonstrate how a few simple adjustments can elevate I/O performance of a file system. We found that file systems available with Red Hat Enterprise Linux 6 delivered better I/O performance than those shipped with Windows Server 2012, in both out-of- the-box and optimized configurations. With I/O performance playing such a critical role in most business applications, selecting the right file system and operating system combination is critical to help you achieve your hardware’s maximum potential. APRIL 2013 A PRINCIPLED TECHNOLOGIES TEST REPORT Commissioned by Red Hat, Inc. About file system and platform configurations While you can use IOzone to gauge disk performance, we concentrated on the file system performance of two operating systems (OSs): Red Hat Enterprise Linux 6, where we examined the ext4 and XFS file systems, and Microsoft Windows Server 2012 Datacenter Edition, where we examined NTFS and ReFS file systems. -
NOVA: a Log-Structured File System for Hybrid Volatile/Non
NOVA: A Log-structured File System for Hybrid Volatile/Non-volatile Main Memories Jian Xu and Steven Swanson, University of California, San Diego https://www.usenix.org/conference/fast16/technical-sessions/presentation/xu This paper is included in the Proceedings of the 14th USENIX Conference on File and Storage Technologies (FAST ’16). February 22–25, 2016 • Santa Clara, CA, USA ISBN 978-1-931971-28-7 Open access to the Proceedings of the 14th USENIX Conference on File and Storage Technologies is sponsored by USENIX NOVA: A Log-structured File System for Hybrid Volatile/Non-volatile Main Memories Jian Xu Steven Swanson University of California, San Diego Abstract Hybrid DRAM/NVMM storage systems present a host of opportunities and challenges for system designers. These sys- Fast non-volatile memories (NVMs) will soon appear on tems need to minimize software overhead if they are to fully the processor memory bus alongside DRAM. The result- exploit NVMM’s high performance and efficiently support ing hybrid memory systems will provide software with sub- more flexible access patterns, and at the same time they must microsecond, high-bandwidth access to persistent data, but provide the strong consistency guarantees that applications managing, accessing, and maintaining consistency for data require and respect the limitations of emerging memories stored in NVM raises a host of challenges. Existing file sys- (e.g., limited program cycles). tems built for spinning or solid-state disks introduce software Conventional file systems are not suitable for hybrid mem- overheads that would obscure the performance that NVMs ory systems because they are built for the performance char- should provide, but proposed file systems for NVMs either in- acteristics of disks (spinning or solid state) and rely on disks’ cur similar overheads or fail to provide the strong consistency consistency guarantees (e.g., that sector updates are atomic) guarantees that applications require. -
Filesystem Considerations for Embedded Devices ELC2015 03/25/15
Filesystem considerations for embedded devices ELC2015 03/25/15 Tristan Lelong Senior embedded software engineer Filesystem considerations ABSTRACT The goal of this presentation is to answer a question asked by several customers: which filesystem should you use within your embedded design’s eMMC/SDCard? These storage devices use a standard block interface, compatible with traditional filesystems, but constraints are not those of desktop PC environments. EXT2/3/4, BTRFS, F2FS are the first of many solutions which come to mind, but how do they all compare? Typical queries include performance, longevity, tools availability, support, and power loss robustness. This presentation will not dive into implementation details but will instead summarize provided answers with the help of various figures and meaningful test results. 2 TABLE OF CONTENTS 1. Introduction 2. Block devices 3. Available filesystems 4. Performances 5. Tools 6. Reliability 7. Conclusion Filesystem considerations ABOUT THE AUTHOR • Tristan Lelong • Embedded software engineer @ Adeneo Embedded • French, living in the Pacific northwest • Embedded software, free software, and Linux kernel enthusiast. 4 Introduction Filesystem considerations Introduction INTRODUCTION More and more embedded designs rely on smart memory chips rather than bare NAND or NOR. This presentation will start by describing: • Some context to help understand the differences between NAND and MMC • Some typical requirements found in embedded devices designs • Potential filesystems to use on MMC devices 6 Filesystem considerations Introduction INTRODUCTION Focus will then move to block filesystems. How they are supported, what feature do they advertise. To help understand how they compare, we will present some benchmarks and comparisons regarding: • Tools • Reliability • Performances 7 Block devices Filesystem considerations Block devices MMC, EMMC, SD CARD Vocabulary: • MMC: MultiMediaCard is a memory card unveiled in 1997 by SanDisk and Siemens based on NAND flash memory. -
Oracle® Linux 7 Working with LXC
Oracle® Linux 7 Working With LXC F32445-02 October 2020 Oracle Legal Notices Copyright © 2020, 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. -
Digital Forensics Focus Area
Digital Forensics Focus Area Barbara Guttman Forensics@NIST November 6, 2020 Digital Forensics – Enormous Scale • Computer crime is now a big volume crime (even worse now that everyone is online) - both in the number of cases and the impacts of the crimes. • Estimate of 6000% increase in spam (claiming to be PPP, WHO) • Most serious crimes have a nexus to digital forensics: Drug dealing uses phones and drones. Murderers communicate with their victims. Financial fraud uses computers. Child sexual exploitation is recorded and shared online. • 2018: Facebook sent 45 million images to LE • Digital Forensics used to support investigations and prosecutions • Used by Forensics Labs, Lawyers, Police Digital Forensics Overview Digital Forensics goal: Provide trustworthy, useful and timely information Digital Forensics has several problems meeting this goal: 1. Overwhelmed with the volume of material 2. Overwhelmed with the variety of material, the constant change and the technical skills needed to understand the material Digital Forensics needs: 1. High quality tools and techniques 2. Help with operational quality and efficiency Digital Forensic Projects • National Software Reference Library • Computer Forensics Tool Testing • Federated Testing • Computer Forensics Reference Dataset • Tool Catalog • Black Box Study and Digital Forensics Scientific Foundation National Software Reference Library (NSRL) The National Software Reference Library (NSRL): • Collects software • Populates a database with software metadata, individual files, file hashes • -
Readahead: Time-Travel Techniques for Desktop and Embedded Systems
Readahead: time-travel techniques for desktop and embedded systems Michael Opdenacker Free Electrons [email protected] Abstract 1.2 Reading ahead Readahead techniques have successfully been used to The idea of reading ahead is to speed up the access to reduce boot time in recent GNU/Linux distributions like a file by preloading at least parts of its contents in page Fedora Core or Ubuntu. However, in embedded sys- cache ahead of time. This can be done when spare I/O tems with scarce RAM, starting a parallel thread read- resources are available, typically when tasks keep the ing ahead all the files used in system startup is no longer processor busy. Of course, this requires the ability to appropriate. The cached pages could be reclaimed even predict the future! before accessing the corresponding files. Fortunately, the systems we are dealing with are pre- This paper will first guide you through the heuristics dictable or even totally predictable in some situations! implemented in kernelspace, as well as through the userspace interface for preloading files or just announc- ing file access patterns. Desktop implementations will • Predictions by watching file read patterns. If pages be explained and benchmarked. We will then detail Free are read from a file in a sequential manner, it makes Electrons’ attempts to implement an easy to integrate sense to go on reading the next blocks in the file, helper program reading ahead files at the most appropri- even before these blocks are actually requested. ate time in the execution flow. • System startup. The system init sequence doesn’t This paper and the corresponding presentation target change. -
Beyond Init: Systemd Linux Plumbers Conference 2010
Beyond Init: systemd Linux Plumbers Conference 2010 Kay Sievers Lennart Poettering November 2010 Kay Sievers, Lennart Poettering Beyond Init: systemd Triggers: Boot, Socket, Bus, Device, Path, Timers, More Kay Sievers, Lennart Poettering Beyond Init: systemd Kay Sievers, Lennart Poettering Beyond Init: systemd Substantial coverage of basic OS boot-up tasks, including fsck, mount, quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Kay Sievers, Lennart Poettering Beyond Init: systemd including fsck, mount, quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, Kay Sievers, Lennart Poettering Beyond Init: systemd mount, quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, including fsck, Kay Sievers, Lennart Poettering Beyond Init: systemd quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, including fsck, mount, Kay Sievers, Lennart Poettering Beyond Init: systemd hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, including fsck, mount, quota, Kay Sievers, Lennart Poettering Beyond Init: systemd readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. -
Outline of Ext4 File System & Ext4 Online Defragmentation Foresight
Outline of Ext4 File System & Ext4 Online Defragmentation Foresight LinuxCon Japan/Tokyo 2010 September 28, 2010 Akira Fujita <[email protected]> NEC Software Tohoku, Ltd. Self Introduction ▐ Name: Akira Fujita Japan ▐ Company: NEC Software Tohoku, Ltd. in Sendai, Japan. Sendai ● ▐ Since 2004, I have been working at NEC Software Tohoku developing Linux file system, mainly ext3 and ● ext4 filesystems. Tokyo Currently, I work on the quality evaluation of ext4 for enterprise use, and also develop the ext4 online defragmentation. Page 2 Copyright(C) 2010 NEC Software Tohoku, Ltd. All Rights Reserved. Outline ▐ What is ext4 ▐ Ext4 features ▐ Compatibility ▐ Performance measurement ▐ Recent ext4 topics ▐ What is ext4 online defrag ▐ Relevant file defragmentation ▐ Current status / future plan Page 3 Copyright(C) 2010 NEC Software Tohoku, Ltd. All Rights Reserved. What is ext4 ▐ Ext4 is the successor of ext3 which is developed to solve performance issues and scalability bottleneck on ext3 and also provide backward compatibility with ext3. ▐ Ext4 development began in 2006. Included in stable kernel 2.6.19 as EXPERIMENTAL (ext4dev). Since kernel 2.6.28, ext4 has been released as stable (Renamed from ext4dev to ext4 in kernel 2.6.28). ▐ Maintainers Theodore Ts'o [email protected] , Andreas Dilger [email protected] ▐ ML [email protected] ▐ Ext4 Wiki http://ext4.wiki.kernel.org Page 4 Copyright(C) 2010 NEC Software Tohoku, Ltd. All Rights Reserved. Ext4 features Page 5 Copyright(C) 2010 NEC Software Tohoku, Ltd. All Rights Reserved. Ext4 features Bigger file/filesystem size support. Compared to ext3, ext4 is: 8 times larger in file size, 65536 times(!) larger in filesystem size. -
Using the Linux NFS Client with IBM System Storage N Series
Front cover Using the Linux NFS Client with IBM System Storage N series Kernel releases and mount options Tuning the Linux client for performance and reliability Utilities to support advanced NFS features Alex Osuna Eva Ho Chuck Lever ibm.com/redbooks International Technical Support Organization Using the Linux NFS Client with IBM System Storage N series May 2007 SG24-7462-00 Note: Before using this information and the product it supports, read the information in “Notices” on page v. First Edition (May 2007) This edition applies to Version 7.1 of Data ONTAP and later. © Copyright International Business Machines Corporation 2007. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . .v Trademarks . vi Preface . vii The team that wrote this book . vii Become a published author . vii Comments welcome. viii Chapter 1. Linux NSF client overview and solution design considerations . 1 1.1 Introduction . 2 1.2 Deciding which Linux NFS client is right for you . 2 1.2.1 Identifying kernel releases . 3 1.2.2 Current Linux distributions . 4 1.2.3 The NFS client in the 2.4 kernel . 5 1.2.4 The NFS client in the 2.6 kernel . 6 1.3 Mount options for Linux NFS clients . 7 1.4 Choosing a network transport protocol . 12 1.5 Capping the size of read and write operations . 16 Chapter 2. Mount options. 19 2.1 Special mount options. 20 2.2 Tuning NFS client cache behavior . 21 2.3 Mounting with NFS version 4 .