can not use 20 gb of internal hdd (/var/lib/ureadahead/debugfs)

Marking as upstream -> ubiquity.

/var/lib/ureadahead/debugfs is just mounted off somewhere on your / filesystem. It has nothing to do with the difference in reported sizes.

The difference is due to a confusion between various tools as to what "GB" means. The installer matches what hard disk manufacturers generally use, so 320 GB = 320 * 1000 * 1000 * 1000 bytes. GParted is apparently reporting in binary units (sometimes spelled "GiB"), and 298.1 GiB = 298.1 * 1024 * 1024 * 1024 bytes, which if you do the sums comes out to about 320.08 GB. So you haven't lost any disk space - you're just seeing different numbers reported by different programs.

Ubuntu has recently adopted a policy stating that: (a) GB must always mean decimal units and GiB must always mean binary units; (b) hard disk sizes are to be reported in decimal units; (c) some other things that aren't relevant here. This policy is controversial for various reasons and we may amend it, but I don't think too many people seriously disagree with the notion that hard disk sizes should be reported in units that match what the label on the disk you bought says, or at least that you should be able to see them in those units.

The installer is abiding by this policy, as in fact it has done since Ubuntu started; but GParted looks as though it ought to be changed to use decimal units rather than binary units.

Actually, I just read your report more closely and noticed that you pointed out that the installer itself reports 298.1 GB on the manual partitioning screen. good point - I'll get that fixed.

Thank you for your explanation about the difference GB and GiB, @Colin.

Could you explain what "/var/lib/ureadahead/debugfs" exactly is?

Sincereley,

Numan.

GParted already uses binary prefixes correctly (and it doesn't make much sense to use decimal prefixes in some parts of the program IMHO, e.g. when editing). Also see bug #538747 for that topic though.

This bug was fixed in the package ubiquity - 2.2.6

---------------
ubiquity (2.2.6) lucid; urgency=low

  [ Evan Dandrea ]
  * Properly set the text for the release notes label after the user
    runs the 'update this installer' option.
  * Correctly set up GtkComboBoxEntry widgets (LP: #539204).
  * In the KDE frontend, call reboot with root privileges and try
    rebooting via dbus only if a KDE dbus session exists (LP: #540856).
  * Remove the apport hook, it lives in Ubuntu's apport package now.
  * Don't let the user select both "Try Ubuntu" and "Install Ubuntu".
  * Provide visual feedback for clicking "Try Ubuntu" in the form of a
    spinning cursor.
  * Automatic update of included source packages: base-installer
    1.103ubuntu5, console-setup 1.34ubuntu12, partman-base 139ubuntu1.

  [ Colin Watson ]
  * If pkgsel/install-language-support is set to false, then don't install
    new language packs from the network, but nevertheless keep any language
    packs that are in the live filesystem (LP: #540878).
  * Install oem-config-kde in the KDE user-setup plugin (LP: #540895).
  * Don't fall through to the failsafe X server if the main X server
    succeeds (LP: #540938).
  * ubiquity-frontend-gtk depends on gksu (LP: #540331).
  * Change .desktop translation domain to ubiquity-desktop (LP: #540936).
  * Report disk sizes in decimal units in the manual partitioner, for
    consistency with partman and to abide by the new units policy
    (LP: #539653).

  [ Mario Limonciello ]
  * Don't delete the cache too early in select_language_packs.

  [ Roman Shtylman ]
  * Fix for 100% cpu usage in kde frontend (LP: #538505)

  [ Michael Terry ]
  * Upstart jobs: start on starting uxlaunch, Moblin's display manager
    (LP: #540257).
 -- Evan Dandrea <email address hidden> Fri, 19 Mar 2010 23:52:24 +0000