Block device compression with the cloop module

DEEP COMPRESSION

Article from Issue 86/2008
Author(s):

The cloop module lets you manage compression at the block device level. Read on to learn how Knoppix and other Live CDs fit all that software on a single disc.

Cloop is a kernel block device module used in Live CDs such as Knoppix. The cloop module allows the system to read compressed data, usually from a file, thus creating compressed virtual disks. Using cloop, a Linux installation of about 2GB fits on a single 700MB CD-R disc. In this article, I look at how cloop works and provide some insight into general kernel structures of a block device. A Unix system traditionally distinguishes between character-based and block-based devices. If you look into the output of ls -l /dev, you will easily recognize these devices by the prefix – c for character-based and b for block-based devices – at the beginning of the output line (see Listing 1).

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy Linux Magazine

SINGLE ISSUES
Print Issues
Digital Issues
 
SUBSCRIPTIONS
Print Subs
Digisubs
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Working with the Kernel

    If you work with third-party hardware drivers, or even if you just need to fix a broken system, someday you might need to upgrade the Linux kernel.

    more »
  • Ask Klaus!
    more »
  • Top 10 Knoppix Rescue Tricks

    The Knoppix Live Linux distro is packed with powerful tools for fixing broken systems. We ask Knoppix creator Klaus Knopper for his favorite Knoppix rescue tricks.

    more »
  • Cover Intro: Kernel Tricks

    Developers are constantly looking for new ways to interact with the versatile Linux kernel. We study some innovative projects leading deep into kernel space.

    more »
  • Knoppix 7.3

    Knoppix 7.3 comprises the current state of Debian GNU/Linux development and comes with the current hardware support of kernel 3.13, a new update function, and extended security and privacy features.

    more »
comments powered by Disqus

Visit Our Shop

Trial Subscription

Digital Subscription

Subscribe

Direct Download

Read full article as PDF:

032-036_cloop.pdf  (728.80 kB)

News

Tag Cloud

Administration Community Desktop Events Hardware Linux Linux Pro Magazine Mobile Programming Software Ubuntu Web Development Windows free software open source