Comment 25 for bug 551965

Release note added:

== Partition alignment changes may break some systems ==

By default, Ubuntu 10.04 LTS aligns partitions on disk to 1 MiB (1048576 bytes) boundaries. This ensures maximum performance on many modern disks, particularly solid state drives but also new "Advanced Format" disks with physical sectors larger than the traditional 512 bytes. Very few systems nowadays need the old alignment, used in the days of MS-DOS when it was useful for partitions to start at the beginning of a cylinder.

In some rare cases, optimal alignment may cause problems. Some BIOS implementations (those on Asus P5P800-MX and Asus P5GZ-MX motherboards) have been reported to hang after installation. It may be difficult to install Microsoft Windows XP and older after installing Ubuntu, although more recent versions of Windows should be compatible with optimal alignment and indeed may produce it themselves. If you find that you need to use the old cylinder alignment instead, then add the {{{partman/alignment=cylinder}}} boot parameter when starting the installer.