2015-08-10 Top | Slides

Refresher on FileSys

Table of Contents

1 File Systems

  1. file-volume = content of a (hard-disk) partition organized into
    1. Directories and Files
    2. List of free blocks
    3. Parameters describing the volume
  2. file system = file volume + code
  3. A HDD or flash storage based file volumes are persistent.
  4. A RAM-"disk" based file volumes are not persistent, but commonly used.

1.1 Operations

  1. mkfs – one a given partition, make an initial file volume. Only the root and lost+found directories are created. List of free blocks etc initialized. Different mkfs for different fs-designs: mkfs.ext4, mkfs.vfat
  2. fsck – check the integrity of a file volume.
  3. mount – take an off-line file-volume and mount it on an existing directory, called mount-point. Depending on the options, the previous contents of the mount-point becomes invisible. The file-volume appears instead.
  4. umount (sic) – unmount, reverse of above.

1.2 ext4

  1. ext4 is a particular design of a Linux native file system. Windows "drivers" exist but may not be reliable. You need to download and install.
  2. ext4 is a journaling file system.
  3. Android formats its internal eMMC storage as ext4.

1.3 vfat

  1. vfat is a particular design of a Windows native file system. Linux is wholly reliable with it. vfat is now a standard part of Linux.
  2. Android formats its internal flash eMMC storage as ext4, and removable uSD cards as (typically) vfat.

1.4 Swap Space

  1. A file volume designed for use in virtual memory (pages, segments).
  2. When swap space is exhausted, machine will "crawl"
  3. If machine has large amounts of physical memory (RAM), swap space is unused.

1.5 Loop Device

  1. Simulation of a file as a block device
  2. file ubuntu-trusty.iso downloaded iso image
  3. # mkdir -p /root/A create mount point
  4. # mount kubuntu-14.04-desktop-amd64.iso /root/A
  5. % df shows /dev/loop1 1041408 1041408 0 100% /root/A

2 References

  1. http://cecs.wright.edu/~pmateti/Courses/2350/ CEG 2350: OS Concepts and Usage This course presents most of our prerequiste materials. Lecture and lab notes are fully on-line.

    CEG 2350 Catalog Description: Introduction to Linux and Windows systems. GUI and Windowing Systems. Files and Directories. Ownership and Sharing. Programs and Processes. System calls, Libraries. Loading. Dynamic linking. Command Line Shells. Scripting languages. Regular expressions. Clients and Servers. Web browser clients and servers. Secure shell, sftp. SSL/TSL. HTTPS. System Administration. 4 credit hours. 3 hours lectures, 2 hours labs. Prerequisites: CS 1180 or CS 2170 (older numbers CS 240 or CS 220) or equivalent.

Copyright © 2014 pmateti@wright.edu • www.wright.edu/~pmateti 2015-08-10