fuel-dev team mailing list archive

[Miroslav Anashkin <manashkin@xxxxxxxxxxxx>]

Hi Dmitriy,

A1. Yes, MySQL+Galera is true master-master solution. While it is possible
and, in case of 6+ nodes even recommended, to set 1-2 Galera nodes as
slaves - for additional data consistency.
Previous Fuel versions use HAProxy as MySQL managing solution.
In case of Mirantis OpenStack (starting from 3.0 or 3.1) MySQL+Galera
cluster is managed by Pacemaker.
There is no single master node in Galera cluster at all - there are nodes
with most recent data replica and nodes which still have to sync with this
recent replica.
Workflow is simple. Node serves new data changing request and increases its
UUID number. All the other nodes must synchronize data with all the nodes
with UUID greater than current.

A2. Yes, CEPH monitors are also master-master.  One of them is periodically
becomes a leader. Leader is the node, which got the most recent cluster map
replica first. Other monitor nodes must sync they cluster map with current
leader. Every monitor node already synced with leader becomes provider and
leader knows which nodes are currently providers. So, leader also tells the
other nodes which provider each of them should use to get data from.
CEPH monitor synchronization algorithm works similar way as Galera, but
CEPH nodes are parted by functionality to monitor nodes and data storage
nodes. In turn, every Galera node has all the same service set on each node.
So, CEPH monitor nodes only manage where the data should be actually stored
and maintain data consistency between OSD nodes.


A3. Additionally to the previous answerers I may add that Neutron is a
router among the other functionality. It is the reason why there are single
entry points.


On Fri, Jan 10, 2014 at 12:18 PM, Dmitriy Novakovskiy <
dnovakovskiy@xxxxxxxxxxxx> wrote:

> Hi guys,
>
> I'm currently kicking off a a project with new customer, and stumbled on
> some holes in my understanding of Mirantis HA architecture.
>
> Can you please help me understand the following:
>
> Q1. MySQL + Galera - is it an active/active HA? I was told/tend to think
> "yes", but want to understand it better. A simple workflow example would
> help
>
> Q2. ceph-mon on controllers - same question as Q1
>
> Q3. Neutron - is it in active/standy HA? I got this understanding from
> docs and want to understand why. I was told that Grizzly and Havanna
> support multiple l3 agents, but we don't leverage it on some reason in Fuel.
>
> Thanks a lot in advance
>
> ---
> Regards,
> Dmitriy
>
> --
> Mailing list: https://launchpad.net/~fuel-dev
> Post to     : fuel-dev@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~fuel-dev
> More help   : https://help.launchpad.net/ListHelp
>
>


-- 

*Kind Regards*

*Miroslav Anashkin**L2 support engineer**,*
*Mirantis Inc.*
*+7(495)640-4944 (office receptionist)*
*+1(650)587-5200 (office receptionist, call from US)*
*35b, Bld. 3, Vorontsovskaya St.*
*Moscow**, Russia, 109147.*

www.mirantis.com

manashkin@xxxxxxxxxxxx