Synnefo » snf-ganeti » ganeti-local

- ``cfgupgrade`` now supports a ``--downgrade`` option to bring the

  configuration back to the previous stable version.

Reverting an upgrade

~~~~~~~~~~~~~~~~~~~~

For going back between revisions (e.g. 2.1.1 to 2.1.0) no manual

intervention is required, as for upgrades.

Starting from version 2.8, ``cfgupgrade`` supports ``--downgrade``

option to bring the configuration back to the previous stable version.

This is useful if you upgrade Ganeti and after some time you run into

problems with the new version. You can downgrade the configuration

without losing the changes made since the upgrade. Any feature not

supported by the old version will be removed from the configuration, of

course, but you get a warning about it. If there is any new feature and

you haven't changed from its default value, you don't have to worry

about it, as it will get the same value whenever you'll upgrade again.

The procedure is similar to upgrading, but please notice that you have to

revert the configuration **before** installing the old version.

#. Ensure no jobs are running (master node only)::

    $ gnt-job list

#. Pause the watcher for an hour (master node only)::

    $ gnt-cluster watcher pause 1h

#. Stop all daemons on all nodes::

    $ /etc/init.d/ganeti stop

#. Backup old configuration (master node only)::

    $ tar czf /var/lib/ganeti-$(date +\%FT\%T).tar.gz -C /var/lib ganeti

#. Run cfgupgrade on the master node::

    $ /usr/lib/ganeti/tools/cfgupgrade --verbose --downgrade --dry-run

    $ /usr/lib/ganeti/tools/cfgupgrade --verbose --downgrade

   You may want to copy all the messages about features that have been

   removed during the downgrade, in case you want to restore them when

   upgrading again.

#. Install the old Ganeti version on all nodes

#. Restart daemons on all nodes::

    $ /etc/init.d/ganeti restart

#. Re-distribute configuration (master node only)::

    $ gnt-cluster redist-conf

#. Restart daemons again on all nodes::

    $ /etc/init.d/ganeti restart

#. Enable the watcher again (master node only)::

    $ gnt-cluster watcher continue

#. Verify cluster (master node only)::

    $ gnt-cluster verify

Ganeti versions, and to roll back. Point-releases are usually

transparent for the admin.