Open Stack

On 26/08, Eugen Block wrote:
> Hi,
>
> just in addition to the previous response, cinder-volume is a stateful
> service and there should be only one instance running. We configured it to
> be bound to the virtual IP controlled by pacemaker, pacemaker also controls
> all stateless services in our environment although it wouldn't be necessary.
> But that way we have all resources at one place and don't need to
> distinguish.
>

Hi,

Small clarification, cinder-volume is not actually stateful.

It is true that historically the cinder-volume service only supported
High Availability in Active-Passive mode and required the configuration
to set the "host" or "backend_host" configuration option to the same
value in all the different controller nodes, so on failover the newly
started service would consider existing resources as its own.

Currently cinder-volume does support Active-Active HA, though not all
drivers support this configuration.  Besides using a driver that
supports A/A, a DLM is also required and needs to be configured in
Cinder, finally the "host" and "backend_host" options must not be
configured and the "cluster" configuration should be configured instead.

Cheers,
Gorka.


>
> Zitat von Satish Patel <satish.txt at gmail.com>:
>
> > Hi,
> >
> > 3 nodes requirements come from MySQL galera and RabbitMQ clustering because
> > of quorum requirements ( it should be in odd numbers 1, 3, 5 etc..). Rest
> > of components works without clustering and they live behind HAProxy LB for
> > load sharing and redundancy.
> >
> > Someone else can add more details here if I missed something.
> >
> > On Thu, Aug 25, 2022 at 4:05 AM 박경원 <park0kyung0won at dgist.ac.kr> wrote:
> >
> > > Hello
> > >
> > >
> > > I have two questions about deploying openstack in high available setup
> > >
> > > Specifically, HA setup for controller nodes
> > >
> > >
> > > 1. Are openstack services (being deployed on controller nodes) stateless?
> > >
> > >
> > > Aside from non-openstack packages(galera/mysql, zeromq, ...) for
> > > infrastructure, are openstack services stateless?
> > >
> > > For example, can I achieve high availability by deploying two nova-api
> > > services to two separate controller nodes
> > >
> > > by load balacing API calls to them through HAproxy?
> > >
> > > Is this(load balancer) the way how openstack achieves high availability?
> > >
> > >
> > >
> > > 2. Why minimum 3 controller nodes for HA?
> > >
> > >
> > > Is this solely due to etcd?
> > >
> > >
> > > Thanks!
> > >
>
>
>
>