Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

e4defrag(8)


NAME

   e4defrag - online defragmenter for ext4 filesystem

SYNOPSIS

   e4defrag [ -c ] [ -v ] target ...

DESCRIPTION

   e4defrag  reduces fragmentation of extent based file. The file targeted
   by e4defrag is created on ext4 filesystem made with "-O extent"  option
   (see  mke2fs(8)).   The  targeted  file gets more contiguous blocks and
   improves the file access speed.

   target is a regular file, a directory, or a device that is  mounted  as
   ext4   filesystem.    If   target  is  a  directory,  e4defrag  reduces
   fragmentation of all files in it. If target is a device, e4defrag  gets
   the  mount  point  of it and reduces fragmentation of all files in this
   mount point.

OPTIONS

   -c     Get a current fragmentation count  and  an  ideal  fragmentation
          count,  and  calculate  fragmentation  score  based  on them. By
          seeing this score, we can determine whether  we  should  execute
          e4defrag  to  target.   When  used  with  -v option, the current
          fragmentation  count  and  the  ideal  fragmentation  count  are
          printed for each file.

          Also this option outputs the average data size in one extent. If
          you see it, you'll find the file has ideal extents or not.  Note
          that  the maximum extent size is 131072KB in ext4 filesystem (if
          block size is 4KB).

          If this option is specified, target is never defragmented.

   -v     Print error messages and  the  fragmentation  count  before  and
          after defrag for each file.

NOTES

   e4defrag does not support swap file, files in lost+found directory, and
   files allocated in indirect blocks. When target is a device or a  mount
   point,  e4defrag  doesn't  defragment  files  in  mount  point of other
   device.

   It safe to run e4defrag on a file  while  it  is  actively  in  use  by
   another  application.   Since  the  contents  of file blocks are copied
   using the page cache, this can result in a performance slowdown to both
   e4defrag and the application due to contention over the system's memory
   and disk bandwidth.

   If the  file  system's  free  space  is  fragmented,  or  if  there  is
   insufficient  free space available, e4defrag may not be able to improve
   the file's fragmentation.

   Non-privileged users can execute e4defrag to their own  file,  but  the
   score  is  not  printed  if  -c  option  is specified. Therefore, it is
   desirable to be executed by root user.

AUTHOR

   Written by Akira Fujita <a-fujita@rs.jp.nec.com> and Takashi  Sato  <t-
   sato@yk.jp.nec.com>.

SEE ALSO

   mke2fs(8), mount(8).



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.



Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.



Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.



Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner