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zRAM Swap Support in Anaconda

The Anaconda installer now supports swap on zRAM during the installation.

zRAM is a standard block device with its contents compressed. Placing swap into such device during the installation allows the installer to store more data in RAM instead of the hard drive. This is especially helpful on systems with low amounts of RAM available - installation on these systems now runs significantly faster. Testing also shows that with zRAM swap, it is now possible to install Fedora on systems with as little as 320 MB RAM.

This feature is automatically enabled if Anaconda detects 2 GB or less memory, and disabled on systems with more than 2 GB RAM. This behavior can be changed by using the inst.zram=on or inst.zram=off boot option at the boot menu to force zRAM swap on or off.

Specific limits, numbers and way of implementation may be changed in the future.

Changes in Anaconda Boot Options

A boot option is an option used to modify the installer's behavior on the boot command line. The following boot options have been added in Fedora 21:

  • inst.zram= - use this option to force zRAM swap on (inst.zram=on) or off (inst.zram=off).
  • inst.dnf - forces Anaconda to use the experimental DNF backend for package installation instead of YUM
  • inst.memcheck - perform a check at the beginning of the installation to see if there is enough available RAM, and stop the installation with an error message if there is not. This option is enabled by default, however, you can use inst.memcheck=0 to it.

Changes in Anaconda Command Line Options

Command line options are used when running the installer from a terminal on an already installed system, for example when installing into a disk image.

  • The built-in help available through anaconda -h now provides descriptions for all available commands.
  • --memcheck: Check if the system has enough RAM to complete the installation and abort if it doesn't. Note that this check is approximate and that memory usage during installation depends on the package selection, user interface (graphical/text) and other parameters.
  • --nomemcheck: Do not check if the system has enough RAM to complete the installation. Note that an attempt to install with less than the safe minimum amount of memory may fail.
  • --leavebootorder: Boot drives in their existing order - used to override the default of booting into the newly installed drive on IBM Power Systems servers and EFI systems. This is useful for systems that, for example, should network boot first before falling back to a local boot.
  • --extlinux: Use extlinux as the boot loader. Note that there is no attempt to validate that this will work for your platform, which means your system may be unable to boot after the installation.
  • --dnf: Use the experimental DNF package management backend instead of the YUM backend that is used by default. For more information about the DNF project, see

Changes in Kickstart Syntax

This section provides a list of changes related to Kickstart commands and options. A list of these changes can also be viewed using the following command: ksverdiff -f F20 -t F21 However, this command will only work on Fedora 21 with the pykickstart package installed.

New Commands and Options

  • fcoe --autovlan: Enable automatic discovery of VLANs.
  • bootloader --disabled: Do not attempt to install a boot loader. This option supersedes all other boot loader configuration - if you use this option, all other bootloader options will be ignored and no boot loader packages will be installed.
  • network --interfacename=: Specify a custom interface name for a virtual LAN device. This option should be used when the default name generated by the --vlanid= option is not desirable. This option must be used along with --vlanid=.
  • ostreesetup: A new command, used to handle an OSTree repository. Available options are:
    • --osname=: Repository name. Mandatory. NEEDINFO
    • --remote=: Optional. NEEDINFO
    • --url=: Repository URL. Mandatory. NEEDINFO
    • --ref=: Mandatory. NEEDINFO
    • --nogpg: Disable GPG key verification.
  • clearpart --disklabel=: Used to create a custom disk label when relabeling disks
  • autopart --fstype=: Allows you to specify a file system type such as ext4 or xfs to use instead of the default when using automatic partitioning.
  • repo --install: NEEDINFO
  • Changes in the %packages section:
    • You can now specify an environment to be installed in the %packages section by adding an environment name prefixed by @^.
    • The %packages --nocore option can be used to disable installing of the Core package group.
    • You can now skip installing the kernel using -kernel.

Changes in Existing Command and Option Behavior

  • The volgroup --pesize option now does not have a default value; this means that you must always use this option to specify the size of the volume group's physical extents. The previous default value was 32768. NEEDINFO

Additional Changes

  • Software RAID configuration in the graphical user interface has been tweaked.
  • You can now use the [+] and [-] keys as shortcuts in the manual partitioning screen in the graphical user interface.
  • The ksverdiff (part of the pykickstart package) has a new option: --listversions. Use this option to list all available operating system versions which can be used as arguments for the --from= and --to= options.

NOTES, do not publicanize

  • Low memory installations work better using methods where squashfs.img doesn't need to be kept in memory, ie nfs,live image. ????