[ClusterLabs] system or ocf resource agent

[Ken Gaillot]

On 07/08/2016 05:10 AM, Heiko Reimer wrote:
> Hi,
> 
> i am setting up new debian 8 ha cluster with drbd, corosync and
> pacemaker with apache and mysql. In my old environment i had configured
> resources with ocf resource agents. Now i have seen that there is
> systemd. Which agent would you recommend?
> 
> 
> Mit freundlichen Grüßen / Best regards
>  
> Heiko Reimer


There's no one answer for all services. Some things to consider:

* Only OCF agents can take parameters, so they may have additional
capabilities that the systemd agent doesn't.

* Only OCF agents can be used for globally unique clones, clones that
require notifications, and multistate (master/slave) resources.

* OCF agents are usually written to support a variety of
OSes/distributions, while systemd unit files are often tailored to the
particular system. This can give OCF an advantage if you have a variety
of OSes and want the resource agent to behave as identically as possible
on all of them, or it can give systemd an advantage if you have a
homogeneous environment and want to use OS-specific facilities as much
as possible.

* A lot depends on the particular service. Is the OCF agent widely used
and actively developed? If so, it is more likely to have better features
and enhanced support for running in a cluster; if not, the systemd unit
may be more up-to-date with recent changes in the underlying service.

* Your Pacemaker version matters. Pacemaker added systemd resource
support in 1.1.8, but there were significant issues until 1.1.13, and
minor but useful fixes since then.