# Revision history [back]

### Question about ceilometer polling services

Hi,

I am new to openstack/ceilometer...

After installing the following openstack (newton) ceilometer polling related packages on one node,

• openstack-ceilometer-polling
• openstack-ceilometer-central
• openstack-ceilometer-ipmi
• openstack-ceilometer-compute

it seems each of them creates a systemd service:

  #/usr/lib/systemd/system/openstack-ceilometer-polling.service
#/usr/lib/systemd/system/openstack-ceilometer-central.service
#/usr/lib/systemd/system/openstack-ceilometer-ipmi.service
#/usr/lib/systemd/system/openstack-ceilometer-compute.service


Looking into the service unit files, it seems central/ipmi/compute are all invoking the same script come with the "openstack-ceilometer-polling" package, which means all 4 services use the same script, just with additional namespace parameters.

My question is, on my single node, if I want to have all 3 polling agents enabled, how to start these 4 systemd services? Or put it in other words, what's the relation among these 4 services (are their dependency or mutually exclusive or some other relationship)?

Thanks, /bruin