[Openstack-operators] Milti-site Keystone & Galera

Jonathan Proulx jon at jonproulx.com
Tue Sep 8 20:44:27 UTC 2015

Hi All,

I'm pretty close to opening a second region in my cloud at a second
physical location.

The plan so far had been to only share keystone between the regions
(nova, glance, cinder etc would be distinct) and implement this by
using MariaDB with galera replication between sites with each site
having it's own gmcast_segment to minimize the long distance catter
plus a 3rd site with a galera arbitrator for the obvious reason.

Today I was warned against using this in a multi writer setup. I'd planned
 on one writer per physical location.

I had been under the impression this was the 'done thing' for
geographically sepperate regions, was I wrong? Should I replicate just
for DR and always pick a single possible remote write site?

site to site link is 2x10G (different physical paths), short link is
2.2ms average latency (2.1ms low, 2.5ms high over 250 packets) long
link shouldn't be much longer but isn't yet complete to test.


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