[Cinder][NFS][Openstack-Ansible] Cinder-Volume Mess - Containers and Metal by Accident

Alan Bishop abishop at redhat.com
Sun Aug 7 19:19:33 UTC 2022


On Sun, Aug 7, 2022 at 8:56 AM Dmitriy Rabotyagov <noonedeadpunk at gmail.com>
wrote:

> Another question - are features that tooz support with etcd enough for
> cinder active/active to work?
>

Here's some general info about running cinder-volume in A/A mode:

- Very few drivers support A/A. Drivers need to explicitly declare their
support, and there's no conformance test to ensure A/A mode actually works
(drivers merely claim it should work). The RBD driver definitely supports
A/A, and NFS is currently *not* supported.

- You need to configure two things for a driver to run A/A; 1) configure
the 'cluster' setting in cinder.conf, 2) you need to configure a suitable
DLM for the [coordination]backend_url in cinder.conf. From a DLM
perspective, your best option is tooz's etcd3gw driver. Bear in mind the
etcd3 driver is deprecated [1].

[1] https://review.opendev.org/c/openstack/tooz/+/833107


> IIRC, for NFS openstack-ansible deploy in active/standby mode by default.
> Only ceph goes "active/active" but we don't define coordination url for
> that - only define cluster_name...
>

As I mentioned above, you definitely need to configure the coordination url
with a suitable DLM for A/A to work properly. Things may seem to work when
doing some light testing, but the cinder-volume services will eventually
start stepping all over each other once the activity load increases.

Alan


> Though, we do provide a role/way to get etcd, so no blocker to get
> coordination_url for cinder if etcd covers all cinder needs
>
> вс, 7 авг. 2022 г., 17:36 Dmitriy Rabotyagov <noonedeadpunk at gmail.com>:
>
>> I have actually a question on unrelated topic, but related to the
>> active/standby of cinder-volume.
>>
>> Is there any way to explicitly tell to the backend that it should be
>> active? As well as would it restore active mode if at some point become
>> unreachable and then restore? Recently I tried to look through docs and
>> config options, but was not able to find an answer.
>>
>> вс, 7 авг. 2022 г., 17:09 Takashi Kajinami <tkajinam at redhat.com>:
>>
>>>
>>> - Usually you need to deploy cinder-volume as an act/sby process. Your
>>> cinder-volume would  run
>>>   on only one of the controller nodes managed by a cluster technology
>>> like pacemaker.
>>>   You can split cinder-volume per backend but in such case you'd run
>>> each c-vol in act/sby mode.
>>>
>>
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