Comment 22 for bug 1621541

With one controller down time is 3-5sec, with two controllers down time is up to 7 secs.
Verified on:
cat /etc/fuel_build_id:
 495
cat /etc/fuel_build_number:
 495
cat /etc/fuel_release:
 9.0
cat /etc/fuel_openstack_version:
 mitaka-9.0
rpm -qa | egrep 'fuel|astute|network-checker|nailgun|packetary|shotgun':
 fuel-migrate-9.0.0-1.mos8662.noarch
 fuel-release-9.0.0-1.mos6359.noarch
 fuel-library9.0-9.0.0-1.mos8662.noarch
 fuel-openstack-metadata-9.0.0-1.mos8915.noarch
 shotgun-9.0.0-1.mos90.noarch
 python-fuelclient-9.0.0-1.mos363.noarch
 fuel-mirror-9.0.0-1.mos158.noarch
 fuel-utils-9.0.0-1.mos8662.noarch
 fuel-provisioning-scripts-9.0.0-1.mos8915.noarch
 fuel-9.0.0-1.mos6359.noarch
 nailgun-mcagents-9.0.0-1.mos782.noarch
 fuel-notify-9.0.0-1.mos8662.noarch
 rubygem-astute-9.0.0-1.mos782.noarch
 fuel-misc-9.0.0-1.mos8662.noarch
 fuel-ostf-9.0.0-1.mos947.noarch
 fuel-ui-9.0.0-1.mos2848.noarch
 fuel-nailgun-9.0.0-1.mos8915.noarch
 network-checker-9.0.0-1.mos77.x86_64
 fuel-agent-9.0.0-1.mos291.noarch
 python-packetary-9.0.0-1.mos158.noarch
 fuelmenu-9.0.0-1.mos276.noarch
 fuel-bootstrap-cli-9.0.0-1.mos291.noarch
 fuel-setup-9.0.0-1.mos6359.noarch