Description of problem:
In a Linode cluster  configured with 256 ceph-osds, 0 clients, 3 ceph-mon, 2 ceph-mgr, I have observed this task in $subject  take a very long time to complete. It appears there is some linear or quadratic behavior with the size of the cluster.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Create a large cluster using steps as outlined on ceph-linode's README. 256 OSDs reliably reproduces the issue.
--forks=50  is not the cause. I've observed the same issue with --forks=5.
Could you give us more information about the setup ?
- ansible version
- containerized deployment
- any other useful configuration variables (ceph overrides, osd scenarios, etc..)
When you said 256 OSDs, I suppose that it's not the number of osd nodes but osd devices right ? If that's true how many dedicated nodes are you using ?
I took a quick look and I don't see any reason why the ceph.conf template generation could take more time with the number of OSDs.
I have more concern about the OSDs count on the ceph_volume task  than the template creation.
Also it could be interesting to run ceph-ansible with the configuration from ansible.cfg  (because it's overrided by linode's launch.sh script) and see the task timing via the profile_tasks callback.
Updating the QA Contact to a Hemant. Hemant will be rerouting them to the appropriate QE Associate.