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On Tue, May 5, 2015 at 11:33 AM, Curtis <serverascode at gmail.com> wrote:

> Do people have any comments or strategies on dealing with Galera
> replication across the WAN using regions? Seems like something to try
> to avoid if possible, though might not be possible. Any thoughts on
> that?
>

We're doing this with good luck.  Few things I'd recommend being aware of:

Set galera_group_segment so that each site is in a separate segment.  This
will make it smarter about doing replication and for state transfer.

Make sure you look at the timers and tunables in Galera and make sure they
make sense for your network.  We've got lots of BW and lowish latency
(37ms), so the defaults have worked pretty well for us.

Make sure that when you do provisioning in one site, you don't have CM
tools in the other site breaking things.  We can ran into issues during our
first deploy like this where Puppet was making a change in one site to a
user, and Puppet in the other site reverted the change nearly immediately.
You may have to tweak your deployment process to deal with that sort of
thing.

Make sure you're running Galera or Galera Arbitrator in enough sites to
maintain quorum if you have issues.  We run 3 nodes in one DC, and 3 nodes
in another DC for Horizon, Keystone and Designate.  We run a Galera
arbitrator in a third DC to settle ties.

Lastly, the obvious one is just to stay up to date on patches.  Galera is
pretty stable, but we have run into bugs that we had to get fixes for.

On Tue, May 5, 2015 at 11:33 AM, Curtis <serverascode at gmail.com> wrote:

> Do people have any comments or strategies on dealing with Galera
> replication across the WAN using regions? Seems like something to try
> to avoid if possible, though might not be possible. Any thoughts on
> that?
>
> Thanks,
> Curtis.
>
> On Mon, May 4, 2015 at 3:11 PM, Jesse Keating <jlk at bluebox.net> wrote:
> > I agree with Subbu. You'll want that to be a region so that the control
> > plane is mostly contained. Only Keystone (and swift if you have that)
> would
> > be doing lots of site to site communication to keep databases in sync.
> >
> > http://docs.openstack.org/arch-design/content/multi_site.html is a good
> read
> > on the topic.
> >
> >
> > - jlk
> >
> > On Mon, May 4, 2015 at 1:58 PM, Allamaraju, Subbu <subbu at subbu.org>
> wrote:
> >>
> >> I suggest building a new AZ (“region” in OpenStack parlance) in the new
> >> location. In general I would avoid setting up control plane to operate
> >> across multiple facilities unless the cloud is very large.
> >>
> >> > On May 4, 2015, at 1:40 PM, Jonathan Proulx <jon at jonproulx.com>
> wrote:
> >> >
> >> > Hi All,
> >> >
> >> > We're about to expand our OpenStack Cloud to a second datacenter.
> >> > Anyone one have opinions they'd like to share as to what I would and
> >> > should be worrying about or how to structure this?  Should I be
> >> > thinking cells or regions (or maybe both)?  Any obvious or not so
> >> > obvious pitfalls I should try to avoid?
> >> >
> >> > Current scale is about 75 hypervisors.  Running juno on Ubuntu 14.04
> >> > using Ceph for volume storage, ephemeral block devices, and image
> >> > storage (as well as object store).  Bulk data storage for most (but by
> >> > no means all) of our workloads is at the current location (not that
> >> > that matters I suppose).
> >> >
> >> > Second location is about 150km away and we'll have 10G (at least)
> >> > between sites. The expansion will be approximately the same size as
> >> > the existing cloud maybe slightly larger and given site capacities the
> >> > new location is also more likely to be where any future grown goes.
> >> >
> >> > Thanks,
> >> > -Jon
> >> >
> >> > _______________________________________________
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> >> > OpenStack-operators at lists.openstack.org
> >> >
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> >>
> >>
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>
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