Open Stack

Major,

in Fuel, we've dealt with this problem for a long time in its varying
degrees of unpleasantness. Some virtualization platforms, such as
VirtualBox, are very prone to time drift. Hardware nodes, thankfully, don't
suffer so badly.

Time sync is very important for RabbitMQ, Corosync, and Ceph, in addition
to those items you mentioned above. I haven't seen swift itself break due
to time issues, but you may be right.

The most ideal situation is to point all hosts to public NTP pool servers.
Barring that, elect 1 host to base its time by its hardware clock, and then
direct all other hosts to sync time against that one host. This has major
issues when you're doing virtual deployments with snapshot/revert and
experiencing major time skew, so you may need extra VM management scripts
to manually sync time again after revert.


Best Regards,
Matthew Mosesohn

On Fri, Sep 18, 2015 at 4:03 PM, Major Hayden <major at mhtx.net> wrote:

> Hey there,
>
> I start working on a bug[1] last night about adding a managed NTP
> configuration to openstack-ansible hosts.  My patch[2] gets chrony up and
> running with configurable NTP servers, but I'm still struggling to meet the
> "Proposal" section of the bug where the author has asked for non-infra
> physical nodes to get their time from the infra nodes.  I can't figure out
> how to make it work for AIO builds when one physical host is part of all of
> the groups. ;)
>
> I'd argue that time synchronization is critical for a few areas:
>
>   1) Security/auditing when comparing logs
>   2) Troubleshooting when comparing logs
>   3) I've been told swift is time-sensitive
>   4) MySQL/Galera don't like time drift
>
> However, there's a strong argument that this should be done by deployers,
> and not via openstack-ansible.  I'm still *very* new to the project and I'd
> like to hear some feedback from other folks.
>
> [1] https://bugs.launchpad.net/openstack-ansible/+bug/1413018
> [2] https://review.openstack.org/#/c/225006/
>
> --
> Major Hayden
>
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