Dfsee Concepts and Q&A
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W4118: Linux File Systems
W4118: Linux file systems Instructor: Junfeng Yang References: Modern Operating Systems (3rd edition), Operating Systems Concepts (8th edition), previous W4118, and OS at MIT, Stanford, and UWisc File systems in Linux Linux Second Extended File System (Ext2) . What is the EXT2 on-disk layout? . What is the EXT2 directory structure? Linux Third Extended File System (Ext3) . What is the file system consistency problem? . How to solve the consistency problem using journaling? Virtual File System (VFS) . What is VFS? . What are the key data structures of Linux VFS? 1 Ext2 “Standard” Linux File System . Was the most commonly used before ext3 came out Uses FFS like layout . Each FS is composed of identical block groups . Allocation is designed to improve locality inodes contain pointers (32 bits) to blocks . Direct, Indirect, Double Indirect, Triple Indirect . Maximum file size: 4.1TB (4K Blocks) . Maximum file system size: 16TB (4K Blocks) On-disk structures defined in include/linux/ext2_fs.h 2 Ext2 Disk Layout Files in the same directory are stored in the same block group Files in different directories are spread among the block groups Picture from Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639 3 Block Addressing in Ext2 Twelve “direct” blocks Data Data BlockData Inode Block Block BLKSIZE/4 Indirect Data Data Blocks BlockData Block Data (BLKSIZE/4)2 Indirect Block Data BlockData Blocks Block Double Block Indirect Indirect Blocks Data Data Data (BLKSIZE/4)3 BlockData Data Indirect Block BlockData Block Block Triple Double Blocks Block Indirect Indirect Data Indirect Data BlockData Blocks Block Block Picture from Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. -
Certifying a File System
Certifying a file system: Correctness in the presence of crashes Tej Chajed, Haogang Chen, Stephanie Wang, Daniel Ziegler, Adam Chlipala, Frans Kaashoek, and Nickolai Zeldovich MIT CSAIL 1 / 28 New file systems (and bugs) are introduced over time Some bugs are serious: security exploits, data loss, etc. File systems are complex and have bugs File systems are complex (e.g., Linux ext4 is ∼60,000 lines of code) and have many bugs: 500 ext3 400 300 200 100 # patches for bugs 0 Jan'04 Jan'05 Jan'06 Jan'07 Jan'08 Jan'09 Jan'10 Jan'11 Cumulative number of patches for file-system bugs in Linux; data from [Lu et al., FAST’13] 2 / 28 Some bugs are serious: security exploits, data loss, etc. File systems are complex and have bugs File systems are complex (e.g., Linux ext4 is ∼60,000 lines of code) and have many bugs: 500 ext3 400 ext4 xfs 300 reiserfs 200 jfs btrfs 100 # patches for bugs 0 Jan'04 Jan'05 Jan'06 Jan'07 Jan'08 Jan'09 Jan'10 Jan'11 Cumulative number of patches for file-system bugs in Linux; data from [Lu et al., FAST’13] New file systems (and bugs) are introduced over time 2 / 28 File systems are complex and have bugs File systems are complex (e.g., Linux ext4 is ∼60,000 lines of code) and have many bugs: 500 ext3 400 ext4 xfs 300 reiserfs 200 jfs btrfs 100 # patches for bugs 0 Jan'04 Jan'05 Jan'06 Jan'07 Jan'08 Jan'09 Jan'10 Jan'11 Cumulative number of patches for file-system bugs in Linux; data from [Lu et al., FAST’13] New file systems (and bugs) are introduced over time Some bugs are serious: security exploits, data loss, etc. -
XFS: There and Back ...And There Again? Slide 1 of 38
XFS: There and Back.... .... and There Again? Dave Chinner <[email protected]> <[email protected]> XFS: There and Back .... and There Again? Slide 1 of 38 Overview • Story Time • Serious Things • These Days • Shiny Things • Interesting Times XFS: There and Back .... and There Again? Slide 2 of 38 Story Time • Way back in the early '90s • Storage exceeding 32 bit capacities • 64 bit CPUs, large scale MP • Hundreds of disks in a single machine • XFS: There..... Slide 3 of 38 "x" is for Undefined xFS had to support: • Fast Crash Recovery • Large File Systems • Large, Sparse Files • Large, Contiguous Files • Large Directories • Large Numbers of Files • - Scalability in the XFS File System, 1995 http://oss.sgi.com/projects/xfs/papers/xfs_usenix/index.html XFS: There..... Slide 4 of 38 The Early Years XFS: There..... Slide 5 of 38 The Early Years • Late 1994: First Release, Irix 5.3 • Mid 1996: Default FS, Irix 6.2 • Already at Version 4 • Attributes • Journalled Quotas • link counts > 64k • feature masks • • XFS: There..... Slide 6 of 38 The Early Years • • Allocation alignment to storage geometry (1997) • Unwritten extents (1998) • Version 2 directories (1999) • mkfs time configurable block size • Scalability to tens of millions of directory entries • • XFS: There..... Slide 7 of 38 What's that Linux Thing? • Feature development mostly stalled • Irix development focussed on CXFS • New team formed for Linux XFS port! • Encumberance review! • Linux was missing lots of bits XFS needed • Lot of work needed • • XFS: There and..... Slide 8 of 38 That Linux Thing? XFS: There and..... Slide 9 of 38 Light that fire! • 2000: SGI releases XFS under GPL • • 2001: First stable XFS release • • 2002: XFS merged into 2.5.36 • • JFS follows similar timeline • XFS: There and.... -
Filesystems HOWTO Filesystems HOWTO Table of Contents Filesystems HOWTO
Filesystems HOWTO Filesystems HOWTO Table of Contents Filesystems HOWTO..........................................................................................................................................1 Martin Hinner < [email protected]>, http://martin.hinner.info............................................................1 1. Introduction..........................................................................................................................................1 2. Volumes...............................................................................................................................................1 3. DOS FAT 12/16/32, VFAT.................................................................................................................2 4. High Performance FileSystem (HPFS)................................................................................................2 5. New Technology FileSystem (NTFS).................................................................................................2 6. Extended filesystems (Ext, Ext2, Ext3)...............................................................................................2 7. Macintosh Hierarchical Filesystem − HFS..........................................................................................3 8. ISO 9660 − CD−ROM filesystem.......................................................................................................3 9. Other filesystems.................................................................................................................................3 -
Acronis® Disk Director® 12 User's Guide
User Guide Copyright Statement Copyright © Acronis International GmbH, 2002-2015. All rights reserved. "Acronis", "Acronis Compute with Confidence", "Acronis Recovery Manager", "Acronis Secure Zone", Acronis True Image, Acronis Try&Decide, and the Acronis logo are trademarks of Acronis International GmbH. Linux is a registered trademark of Linus Torvalds. VMware and VMware Ready are trademarks and/or registered trademarks of VMware, Inc. in the United States and/or other jurisdictions. Windows and MS-DOS are registered trademarks of Microsoft Corporation. All other trademarks and copyrights referred to are the property of their respective owners. Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. Distribution of this work or derivative work in any standard (paper) book form for commercial purposes is prohibited unless prior permission is obtained from the copyright holder. DOCUMENTATION IS PROVIDED "AS IS" AND ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE DISCLAIMED, EXCEPT TO THE EXTENT THAT SUCH DISCLAIMERS ARE HELD TO BE LEGALLY INVALID. Third party code may be provided with the Software and/or Service. The license terms for such third-parties are detailed in the license.txt file located in the root installation directory. You can always find the latest up-to-date list of the third party code and the associated license terms used with the Software and/or Service at http://kb.acronis.com/content/7696 Acronis patented technologies Technologies, used in this product, are covered and protected by one or more U.S. -
Journaling File Systems
Linux Journaling File Systems Linux onzSeries Journaling File Systems Volker Sameske ([email protected]) Linux on zSeries Development IBM Lab Boeblingen, Germany Share Anaheim,California February27 –March 4,2005 Session 9257 ©2005 IBM Corporation Linux Journaling File Systems Agenda o File systems. • Overview, definitions. • Reliability, scalability. • File system features. • Common grounds & differences. o Volume management. • LVM, EVMS, MD. • Striping. o Measurement results. • Hardware/software setup. • throughput. • CPU load. 2 Session 9257 © 2005 IBM Corporation Linux Journaling File Systems A file system should... o ...store data o ...organize data o ...administrate data o ...organize data about the data o ...assure integrity o ...be able to recover integrity problems o ...provide tools (expand, shrink, check, ...) o ...be able to handle many and large files o ...be fast o ... 3 Session 9257 © 2005 IBM Corporation Linux Journaling File Systems File system-definition o Informally • The mechanism by which computer files are stored and organized on a storage device. o More formally, • A set of abstract data types that are necessary for the storage, hierarchical organization, manipulation, navigation, access and retrieval of data. 4 Session 9257 © 2005 IBM Corporation Linux Journaling File Systems Why a journaling file system? o Imagine your Linux system crashs while you are saving an edited file: • The system crashs after the changes have been written to disk à good crash • The system crashs before the changes have been written to disk à bad crash but bearable if you have an older version • The sytem crashs just in the moment your data will be written: à very bad crash your file could be corrupted and in worst case the file system could be corrupted à That‘s why you need a journal 5 Session 9257 © 2005 IBM Corporation Linux Journaling File Systems Somefilesystemterms o Meta data • "Data about the data" • File system internal data structure (e.g. -
Warpstock 2018 Presentations Presenter Session Title Notes
Warpstock 2018 Presentations Presenter Session Title Notes Joe Suttle Public Speaking - You CAN do it! Lewis Rosenthal ArcaOS update In this session, Lewis Rosenthal, Managing Member of Arca Noae, LLC, will provide an update on the status of the 5.0 release cycle and expectations for 5.1. Lewis Rosenthal Creating an ArcaOS How to create an ArcaOS installation stick without an Session (1/2 slot) Bootable USB Stick OS/2, eCS, or ArcaOS system already up and running. from ANY Major OS Following onto the well-received session at Warpstock (with live demo) Europe this year, this edition will feature a live demonstration so that the audience may get a feel for walking through the process and just how quick it really is from start to finish. Lewis Rosenthal Forking an Open This session will discuss the reasoning behind splitting a Source Project: Why, project and taking the code in a different direction from the When, and How main development team. Sometimes, the issues are technological in nature, at other times, philosophical or even political. In no event, however, should the decision to fork be taken lightly or without great care. Afterward, providing clarity on the differences between the fork and the original project, without promoting disharmony, presents challenges of its own. Lewis Rosenthal DOS and WinOS/2 on What works, what doesn't, what Arca Noae is trying to do modern systems with about it, and how long that might take. Issues concern a ArcaOS broad range of brief topic points including long filenames, FAT32, extended attributes, memory management, video, and audio functionality. -
Arcaos 5.0 Air-BOOT Supplementary Guide
ArcaOS 5.0 AiR-BOOT Supplementary Guide May 2017 (revision 1) Content Copyright © 2014-2017 Arca Noae, LLC. All rights reserved. http://www.arcanoae.com AiR-BOOT Boot Manager ArcaOS comes with the AiR-BOOT Boot Manager, which is capable of starting ArcaOS from either primary or logical partitions as well as starting other operating systems. The AiR-BOOT Boot Manager is an alternative boot loader which aims to address some of the issues inherent in the IBM Boot Manager on modern systems. AiR-BOOT Features AiR-BOOT does not need a primary partition AiR-BOOT is a TRACK0 loader, so it does not require a partition of its own. Thus, it does not consume one of the four primary partitions available in an MBR partitioning scheme. This does not mean it is always possible to use AiR-BOOT. The size of the first track needs to be at least 63 sectors of 512 bytes. Furthermore, aside from the presence of the MBR, the first track has no official designation and it is known that other disk management software may utilize the first track for its own purposes. AiR-BOOT cannot be used if such other disk management software uses the space in the first track. AiR-BOOT supports huge disks AiR-BOOT is very much OS/2-aware, and thus ArcaOS-aware and is capable of handling the extended geometry used by ArcaOS on disks larger than 512GB. For this it uses the LVM information, so it is mandatory that is information is correct and adequately resembles the disk geometry used by ArcaOS. -
Txwindows, a Multi-Platform Text Mode Windowing Library
TxWin, a multi platform text mode windowing library Jan van Wijk A library for development of text mode applications using a windowing system including menus, dialogs and more ... Presentation contents What & Why, text-mode windowing Main features of the Txwin library Some samples and demos Current shortcomings, future ... Availability and licencing TxWin 5.xx, a text mode windowing library © 2018 JvW What is ... A text mode windowing system (UI) A user interface based on the well-known principles of GUI's like Windows and OS2-PM, but operating entirely with text screen elements (ASCII, ANSI ...) Uses UI elements like windows, buttons, lists, menus, entry fields; Is operated using keyboard and mouse. As opposed to: Graphical User Interface (GUI) environments Simple STDIO based text applications that only use the keyboard and simple sequential output to the screen TxWin 5.xx, a text mode windowing library © 2018 JvW Why text mode windowing Portable to many platforms Fast, even on old hardware Works in minimal environments like boot diskettes/CDROM (OS2, DOS, Linux ...) Appeals to command line users TxWin 5.xx, a text mode windowing library © 2018 JvW Main features Multi-platform, currently available on: DOS, 32-bits, using a DOS-extender (DOS32A) OS/2, 32-bits only, OS/2 2.x and later, ArcaOS, eCS Windows 32-bit, XP and later (no 9x or NT4) Linux, works on most distributions, console or xterm MacOS, 64 bit runs in Terminal or iTerm, API much like OS2-PM or Windows Message based, extendable to a certain degree using -
Reliability, Transactions, Distributed Systems
Important “ilities” CS162 • Availability: the probability that the system can accept and process Operating Systems and requests – Often measured in “nines” of probability. So, a 99.9% probability is Systems Programming considered “3-nines of availability” Lecture 20 – Key idea here is independence of failures • Durability: the ability of a system to recover data despite faults Reliability, Transactions – This idea is fault tolerance applied to data Distributed Systems – Doesn’t necessarily imply availability: information on pyramids was very durable, but could not be accessed until discovery of Rosetta Stone November 6th, 2017 • Reliability: the ability of a system or component to perform its Prof. Ion Stoica required functions under stated conditions for a specified period of time (IEEE definition) http://cs162.eecs.Berkeley.edu – Usually stronger than simply availability: means that the system is not only “up”, but also working correctly – Includes availability, security, fault tolerance/durability – Must make sure data survives system crashes, disk crashes, etc 11/6/17 CS162 © UCB Fall 2017 Lec 20.2 How to Make File System Durable? RAID: Redundant Arrays of Inexpensive Disks • Disk blocks contain Reed-Solomon error correcting codes (ECC) to deal with small defects in disk drive • Invented by David Patterson, Garth A. Gibson, and – Can allow recovery of data from small media defects Randy Katz here at UCB in 1987 • Make sure writes survive in short term – Either abandon delayed writes or • Data stored on multiple disks (redundancy) -
Partitioning Disks with Parted
Partitioning Disks with parted Author: Yogesh Babar Technical Reviewer: Chris Negus 10/6/2017 Storage devices in Linux (such as hard drives and USB drives) need to be structured in some way before use. In most cases, large storage devices are divided into separate sections, which in Linux are referred to as partitions. A popular tool for creating, removing and otherwise manipulating disk partitions in Linux is the parted command. Procedures in this tech brief step you through different ways of using the parted command to work with Linux partitions. UNDERSTANDING PARTED The parted command is particularly useful with large disk devices and many disk partitions. Differences between parted and the more common fdisk and cfdisk commands include: • GPT Format: The parted command can create can be used to create Globally Unique Identifiers Partition Tables (GPT), while fdisk and cfdisk are limited to msdos partition tables. • Larger disks: An msdos partition table can only format up to 2TB of disk space (although up to 16TB is possible in some cases). A GPT partition table, however, have the potential to address up to 8 zebibytes of space. • More partitions: Using primary and extended partitions, msdos partition tables allow only 16 partitions. With GPT, you get up to 128 partitions by default and can choose to have many more. • Reliability: Only one copy of the partition table is stored in an msdos partition. GPT keeps two copies of the partition table (at the beginning and end of the disk). The GPT also uses a CRC checksum to check the partition table's integrity (which is not done with msdos partitions). -
Data Interchange & Optical Standards
311 East Carrillo Street Santa Barbara, CA 93101 Telephone (805) 963-3853 Fax (805) 962-1541 Email: [email protected] http://www.osta.org Data Interchange & Optical Standards February 12, 1996 Revision 2 Data Interchange and Optical Standards Optical disk media provides high capacity removable storage with an extremely long life. The removability of the media provides us with the opportunity to easily transport and interchange of large amounts of data. The goal of data interchange is to have the ability to store files on optical media using any type of computer and then be able to access these files using any other computer system. Removable media data interchange occurs at three different levels: sector, file and application. Sector Level Interchange Sector interchange is the ability to interchange data at the sector level. This level of interchange defines the ability to move media universally among different optical drives. The data being interchanged at this level is comprised of sectors. When it is stated that two different optical drives can interchange data at the sector level, it means that the drives can read and write sectors on media created by each other. For example, assume you have two optical drives, one manufactured by company A and the other drive by company B, and you write to sectors 100 through 200 on an optical disk in drive A. With sector level interchange, you can place the disk in drive B and read sectors 100 through 200 that were written by drive A. You can then write to sectors 300 through 400 on the disk with drive B, and then move the disk back to drive A and read the sectors written by drive B.