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DASH: Database Shadowing for Mobile DBMS
DASH: Database Shadowing for Mobile DBMS Youjip Won1 Sundoo Kim2 Juseong Yun2 Dam Quang Tuan2 Jiwon Seo2 1KAIST, Daejeon, Korea 2Hanyang University, Seoul, Korea [email protected] [email protected] ABSTRACT 1. INTRODUCTION In this work, we propose Database Shadowing, or DASH, Crash recovery is a vital part of DBMS design. Algorithms which is a new crash recovery technique for SQLite DBMS. for crash recovery range from naive full-file shadowing [15] DASH is a hybrid mixture of classical shadow paging and to the sophisticated ARIES protocol [38]. Most enterprise logging. DASH addresses four major issues in the current DBMS's, e.g., IBM DB2, Informix, Micrsoft SQL and Oracle SQLite journal modes: the performance and write amplifi- 8, use ARIES or its variants for efficient concurrency control. cation issues of the rollback mode and the storage space re- SQLite is one of the most widely used DBMS's. It is quirement and tail latency issues of the WAL mode. DASH deployed on nearly all computing platform such as smart- exploits two unique characteristics of SQLite: the database phones (e.g, Android, Tizen, Firefox, and iPhone [52]), dis- files are small and the transactions are entirely serialized. tributed filesystems (e.g., Ceph [58] and Gluster filesys- DASH consists of three key ingredients Aggregate Update, tem [1]), wearable devices (e.g., smart watch [4, 21]), and Atomic Exchange and Version Reset. Aggregate Update elim- automobiles [19, 55]. As a library-based embedded DBMS, inates the redundant write overhead and the requirement to SQLite deliberately adopts a basic transaction management maintain multiple snapshots both of which are inherent in and crash recovery scheme. -
Firewalld ↔ Iptables (Continued)
firewalld ↔ iptables (continued) Or, better said as, Understanding Linux Firewall Changes and Tools A firewall evolution and system management process Presented to SLUUG By David Forrest August 9, 2017 Bio I am David Forrest, a businessman in the housing and construction materials industry. Always keen to use the open and supportable solution even if it means getting my hands dirty. I was there, I did that, I have the t-shirt. And, I'm retired so now I can work on the “bleeding edge” - so on to the testing kernel! Why tonight? Why should we switch to firewalld? I felt a continuation was in order to address the problems that are caused by the virtual world and the interaction of processes within today's machines. Our various distributions seem to be jumping to the systemd init setup as it appears to offer better administration control to Linux Kernel machines. Firewalld just one of many efforts to see the future. In recent years, operating system virtualization has taken the industry by storm. But I'm still on CentOS7 and it uses firewalld as its default firewall along with systemd https://wiki.debian.org/Debate/initsystem/systemd firewalld It's a daemon and a command line interface to all the backends! One can start it as a service with a default setup and change it dynamically with a command line or with the daemon using D-Bus or NetworkManager. And with the new nftables release, we'll be able to combine several rules in one rich rule. The firewalld Architecture Firewalld and nft Systems have also moved toward Software Defined Networking (SDN) and system density has increased. -
Hardening Linux
eBooks-IT.org 4444_FM_final.qxd 1/5/05 12:39 AM Page i eBooks-IT.org Hardening Linux JAMES TURNBULL 4444_FM_final.qxd 1/5/05 12:39 AM Page ii eBooks-IT.org Hardening Linux Copyright © 2005 by James Turnbull All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. ISBN (pbk): 1-59059-444-4 Printed and bound in the United States of America 987654321 Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Lead Editor: Jim Sumser Technical Reviewer: Judith Myerson Editorial Board: Steve Anglin, Dan Appleman, Ewan Buckingham, Gary Cornell, Tony Davis, Jason Gilmore, Chris Mills, Dominic Shakeshaft, Jim Sumser Project Manager: Kylie Johnston Copy Edit Manager: Nicole LeClerc Copy Editor: Kim Wimpsett Production Manager: Kari Brooks-Copony Production Editor: Kelly Winquist Compositor: Linda Weidemann Proofreader: Lori Bring Indexer: Kevin Broccoli Artist: Kinetic Publishing Services, LLC Cover Designer: Kurt Krames Manufacturing Manager: Tom Debolski Distributed to the book trade in the United States by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY 10013, and outside the United States by Springer-Verlag GmbH & Co. KG, Tiergartenstr. 17, 69112 Heidelberg, Germany. In the United States: phone 1-800-SPRINGER, fax 201-348-4505, e-mail [email protected], or visit http://www.springer-ny.com. -
CS 152: Computer Systems Architecture Storage Technologies
CS 152: Computer Systems Architecture Storage Technologies Sang-Woo Jun Winter 2019 Storage Used To be a Secondary Concern Typically, storage was not a first order citizen of a computer system o As alluded to by its name “secondary storage” o Its job was to load programs and data to memory, and disappear o Most applications only worked with CPU and system memory (DRAM) o Extreme applications like DBMSs were the exception Because conventional secondary storage was very slow o Things are changing! Some (Pre)History Magnetic core memory Rope memory (ROM) 1960’s Drum memory 1950~1970s 72 KiB per cubic foot! 100s of KiB (1024 bits in photo) Hand-woven to program the 1950’s Apollo guidance computer Photos from Wikipedia Some (More Recent) History Floppy disk drives 1970’s~2000’s 100 KiBs to 1.44 MiB Hard disk drives 1950’s to present MBs to TBs Photos from Wikipedia Some (Current) History Solid State Drives Non-Volatile Memory 2000’s to present 2010’s to present GB to TBs GBs Hard Disk Drives Dominant storage medium for the longest time o Still the largest capacity share Data organized into multiple magnetic platters o Mechanical head needs to move to where data is, to read it o Good sequential access, terrible random access • 100s of MB/s sequential, maybe 1 MB/s 4 KB random o Time for the head to move to the right location (“seek time”) may be ms long • 1000,000s of cycles! Typically “ATA” (Including IDE and EIDE), and later “SATA” interfaces o Connected via “South bridge” chipset Ding Yuan, “Operating Systems ECE344 Lecture 11: File -
AMD Alchemy™ Processors Building a Root File System for Linux® Incorporating Memory Technology Devices
AMD Alchemy™ Processors Building a Root File System for Linux® Incorporating Memory Technology Devices 1.0 Scope This document outlines a step-by-step process for building and deploying a Flash-based root file system for Linux® on an AMD Alchemy™ processor-based development board, using an approach that incorporates Memory Technology Devices (MTDs) with the JFFS2 file system. Note: This document describes creating a root file system on NOR Flash memory devices, and does not apply to NAND Flash devices. 1.1 Journaling Flash File System JFFS2 is the second generation of the Journaling Flash File System (JFFS). This file system provides a crash-safe and powerdown-safe Linux file system for use with Flash memory devices. The home page for the JFFS project is located at http://developer.axis.com/software/jffs. 1.2 Memory Technology Device The MTD subsystem provides a generic Linux driver for a wide range of memory devices, including Flash memory devices. This driver creates an abstracted device used by JFFS2 to interface to the actual Flash memory hardware. The home page for the MTD project is located at http://www.linux-mtd.infradead.org. 2.0 Building the Root File System Before being deployed to an AMD Alchemy platform, the file system must first be built on an x86 Linux host PC. The pri- mary concern when building a Flash-based root file system is often the size of the image. The file system must be designed so that it fits within the available space of the Flash memory, with enough extra space to accommodate any runtime-created files, such as temporary or log files. -
Recursive Updates in Copy-On-Write File Systems - Modeling and Analysis
2342 JOURNAL OF COMPUTERS, VOL. 9, NO. 10, OCTOBER 2014 Recursive Updates in Copy-on-write File Systems - Modeling and Analysis Jie Chen*, Jun Wang†, Zhihu Tan*, Changsheng Xie* *School of Computer Science and Technology Huazhong University of Science and Technology, China *Wuhan National Laboratory for Optoelectronics, Wuhan, Hubei 430074, China [email protected], {stan, cs_xie}@hust.edu.cn †Dept. of Electrical Engineering and Computer Science University of Central Florida, Orlando, Florida 32826, USA [email protected] Abstract—Copy-On-Write (COW) is a powerful technique recursive update. Recursive updates can lead to several for data protection in file systems. Unfortunately, it side effects to a storage system, such as write introduces a recursively updating problem, which leads to a amplification (also can be referred as additional writes) side effect of write amplification. Studying the behaviors of [4], I/O pattern alternation [5], and performance write amplification is important for designing, choosing and degradation [6]. This paper focuses on the side effects of optimizing the next generation file systems. However, there are many difficulties for evaluation due to the complexity of write amplification. file systems. To solve this problem, we proposed a typical Studying the behaviors of write amplification is COW file system model based on BTRFS, verified its important for designing, choosing, and optimizing the correctness through carefully designed experiments. By next generation file systems, especially when the file analyzing this model, we found that write amplification is systems uses a flash-memory-based underlying storage greatly affected by the distributions of files being accessed, system under online transaction processing (OLTP) which varies from 1.1x to 4.2x. -
F2punifycr: a Flash-Friendly Persistent Burst-Buffer File System
F2PUnifyCR: A Flash-friendly Persistent Burst-Buffer File System ThanOS Department of Computer Science Florida State University Tallahassee, United States I. ABSTRACT manifold depending on the workloads it is handling for With the increased amount of supercomputing power, applications. In order to leverage the capabilities of burst it is now possible to work with large scale data that buffers to the utmost level, it is very important to have a pose a continuous opportunity for exascale computing standardized software interface across systems. It has to that puts immense pressure on underlying persistent data deal with an immense amount of data during the runtime storage. Burst buffers, a distributed array of node-local of the applications. persistent flash storage devices deployed on most of Using node-local burst buffer can achieve scalable the leardership supercomputers, are means to efficiently write bandwidth as it lets each process write to the handling the bursty I/O invoked through cutting-edge local flash drive, but when the files are shared across scientific applications. In order to manage these burst many processes, it puts the management of metadata buffers, many ephemeral user level file system solutions, and object data of the files under huge challenge. In like UnifyCR, are present in the research and industry order to handle all the challenges posed by the bursty arena. Because of the intrinsic nature of the flash devices and random I/O requests by the Scientific Applica- due to background processing overhead, like Garbage tions running on leadership Supercomputing clusters, Collection, peak write bandwidth is hard to get. -
Demystifying Internet of Things Security Successful Iot Device/Edge and Platform Security Deployment — Sunil Cheruvu Anil Kumar Ned Smith David M
Demystifying Internet of Things Security Successful IoT Device/Edge and Platform Security Deployment — Sunil Cheruvu Anil Kumar Ned Smith David M. Wheeler Demystifying Internet of Things Security Successful IoT Device/Edge and Platform Security Deployment Sunil Cheruvu Anil Kumar Ned Smith David M. Wheeler Demystifying Internet of Things Security: Successful IoT Device/Edge and Platform Security Deployment Sunil Cheruvu Anil Kumar Chandler, AZ, USA Chandler, AZ, USA Ned Smith David M. Wheeler Beaverton, OR, USA Gilbert, AZ, USA ISBN-13 (pbk): 978-1-4842-2895-1 ISBN-13 (electronic): 978-1-4842-2896-8 https://doi.org/10.1007/978-1-4842-2896-8 Copyright © 2020 by The Editor(s) (if applicable) and The Author(s) This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Open Access This book is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made. The images or other third party material in this book are included in the book’s Creative Commons license, unless indicated otherwise in a credit line to the material. -
Zálohuj S BTRFS!
Zalohuj´ s BTRFS! Bc . Josef Jebavy´ www.josefjebavy.cz 3. 11. 2018 Bc . Josef Jebavy´ Zalohuj´ s BTRFS! whoami Bc. Josef Jebavy´ Linux admin Vyvoj´ a´rˇ software Clenˇ Geeklab a prˇ´ıznivec OpenAlt Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Osnova 1 Zalohov´ an´ ´ı 2 Filesystemy´ Filesystemy´ 3 Btrfs 4 RAID 5 Btrfs vsudeˇ 6 Fstab 7 Grub 8 UEFI 9 Snapshot Create Delete 10 Informace filesystem´ u˚ 11 Zkusenostiˇ 12 Odkazy 13 Dotazy, skolenˇ ´ı, kontakt Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Ulo´ znˇ a´ media´ Rotacnˇ ´ı SSD (TRIM) CD/DVD Pasky´ Bc . Josef Jebavy´ Zalohuj´ s BTRFS! cetnostˇ zalohov´ an´ ´ı, archivace lokace medium nastroje´ kontrola, obnoven´ı Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Filesystem´ Co je filesystem?´ Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Filesystemy:´ FAT32, NTFS (1993) ext3(2001),ext3(2004), RaiseFS, JFS, HFS (1985), HFS+ (1998, b-trees) ZFS (2005) JFFS, UBIFS BTRFS(2009) Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Vlastnosti Aneb procˇ pouzˇ´ıvat BTRFS: B-tree file system vyvoj´ od roku 2007 copy-on-write kontroln´ı souctyˇ RAID 0,1 komprese snapshoty-zalohov´ an´ ´ı send/receive zmenyˇ za chodu obdoba ZFS - licecnˇ ´ı nekompatibilita TRIM Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Zat´ım ve vyvoji´ RAID 5,6 Sifrovˇ an´ ´ı Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Podpora Podporovane´ platformy Linux x86 i ARM atd. Prˇ´ımo soucˇast´ linuxoveho´ jadra´ - od verze 2.6.29-rc1 Bc . Josef Jebavy´ Zalohuj´ s BTRFS! Zkusenostiˇ Ja´ od roku 2013 Btrfs btrfs-progs (jul 2018 v4.17) Odlisnˇ e´ Hodneˇ moznostˇ ´ı Manual´ Bc . -
Migrazione Da Iptables a Nftables
UNIVERSITÀ DEGLI STUDI DI GENOVA MASTER IN CYBER SECURITY AND DATA PROTECTION Migrazione da iptables a nftables Autore: Tutor accademico: dott. Marco DE BENEDETTO prof. Mario MARCHESE Tutor aziendale: dott. Carlo BERUTTI BERGOTTO Project Work finale del Master di secondo livello in Cyber Security and Data Protection III edizione (a.a. 2016/17) 10 marzo 2019 iii Indice 1 Introduzione 1 2 Packet Filtering in Linux 3 2.1 Storia ...................................... 3 2.2 Netfilter .................................... 4 2.3 Nftables successore di iptables? ....................... 6 3 Firewall Linux nella rete Galliera 7 3.1 Cenni storici .................................. 7 3.2 Architettura attuale .............................. 7 3.3 Problemi dell’infrastruttura ......................... 9 3.4 Opportunità di migrazione a nftables ................... 9 4 Nftables 11 4.1 Caratteristiche di nftables .......................... 11 4.2 Packet flow in nftables ............................ 12 4.3 Strumenti di debug e tracing ......................... 15 5 Migrazione del Captive Portal 17 5.1 Captive Portal con iptables .......................... 17 5.2 Captive Portal nella versione nftables ................... 19 5.3 Autorizzazioni temporizzate ........................ 20 5.4 Aggiornamento del timeout ......................... 21 5.5 Limitazione della banda ........................... 22 6 Strumenti di sviluppo e test 25 6.1 Virtualizzazione ................................ 25 6.2 Debug ..................................... 26 7 Considerazioni finali -
FRASH: Hierarchical File System for FRAM and Flash
FRASH: Hierarchical File System for FRAM and Flash Eun-ki Kim 1,2 Hyungjong Shin 1,2 Byung-gil Jeon 1,2 Seokhee Han 1 Jaemin Jung 1 Youjip Won 1 1Dept. of Electronics and Computer Engineering, Hanyang University, Seoul, Korea 2Samsung Electronics Co., Seoul, Korea [email protected] Abstract. In this work, we develop novel file system, FRASH, for byte- addressable NVRAM (FRAM[1]) and NAND Flash device. Byte addressable NVRAM and NAND Flash is typified by the DRAM-like fast access latency and high storage density, respectively. Hierarchical storage architecture which consists of byte-addressable NVRAM and NAND Flash device can bring synergy and can greatly enhance the efficiency of file system in various aspects. Unfortunately, current state of art file system for Flash device is not designed for byte-addressable NVRAM with DRAM-like access latency. FRASH file system (File System for FRAM an NAND Flash) aims at exploiting physical characteristics of FRAM and NAND Flash device. It effectively resolves long mount time issue which has long been problem in legacy LFS style NAND Flash file system. In FRASH file system, NVRAM is mapped into memory address space and contains file system metadata and file metadata information. Consistency between metadata in NVRAM and data in NAND Flash is maintained via transaction. In hardware aspect, we successfully developed hierarchical storage architecture. We used 8 MByte FRAM which is the largest chip allowed by current state of art technology. We compare the performance of FRASH with legacy Its-style file system for NAND Flash. FRASH file system achieves x5 improvement in file system mount latency. -
Journaling File Systems
JOURNALING FILE SYSTEMS CS124 – Operating Systems Spring 2021, Lecture 26 2 File System Robustness • The operating system keeps a cache of filesystem data • Secondary storage devices are much slower than main memory • Caching frequently-used disk blocks in memory yields significant performance improvements by avoiding disk-IO operations • ProBlem 1: Operating systems crash. Hardware fails. • ProBlem 2: Many filesystem operations involve multiple steps • Example: deleting a file minimally involves removing a directory entry, and updating the free map • May involve several other steps depending on filesystem design • If only some of these steps are successfully written to disk, filesystem corruption is highly likely 3 File System Robustness (2) • The OS should try to maintain the filesystem’s correctness • …at least, in some minimal way… • Example: ext2 filesystems maintain a “mount state” in the filesystem’s superBlock on disk • When filesystem is mounted, this value is set to indicate how the filesystem is mounted (e.g. read-only, etc.) • When the filesystem is cleanly unmounted, the mount-state is set to EXT2_VALID_FS to record that the filesystem is trustworthy • When OS starts up, if it sees an ext2 drive’s mount-state as not EXT2_VALID_FS, it knows something happened • The OS can take steps to verify the filesystem, and fix it if needed • Typically, this involves running the fsck system utility • “File System Consistency checK” • (Frequently, OSes also run scheduled filesystem checks too) 4 The fsck Utility • To verify the filesystem,