Hey Deepa, We have done this in the past with an old HP MSA appliance and ceph. Deploying this with cross az disabled will work fine, as long as the compute nodes have access to the storage backend and the necessary config is done.

In order to create a volume type, you need to go to the admin section in the dashboard or via the Cli and create a new volume type. Then add extra specs and add backend_name = the name you gave it on the cinder config. Then you can select where you want to create the volume from the drop down or via cli. Bear in mind you need to create the volume type for each backen of you make more than one available.

Hope this helps. //florian

On 14. Oct 2020, at 20.13, Deepa KR deepa.kr@fingent.com wrote:

 Hello Sean

Thanks much for the detailed response.

I am still unclear on below points

if you have cross az attach disable in nova and you want all type/backend to be accessible in all AZ you need to deploy a instance of the cinder volume driver for each of the types in each az.

"deploy a instance of the cinder volume driver for each of the types in each az" <<<< How can i achieve above mentioned thing

i don't know if that answers your question or not but volume types are the way to request a specific backend at the api level. <<< i see volume type option while creating volume .. But when I am trying to launch an instance I don't see that parameter in Horizon .. may be in the command line we have (not sure though) . Is this something that needs to be handled at AZ level ?

...

On Wed, Oct 14, 2020 at 7:29 PM Sean Mooney smooney@redhat.com wrote: On Wed, 2020-10-14 at 18:38 +0530, Deepa KR wrote:

...

Hi All

Good Day

From documentation we are able to understand that we can configure multiple backends for cinder (Ceph ,External Storage device or NFS etc) Is there any way we can choose the backend while instance launching .Say

...

instance1 backend should be from an external storage device like EMC and instance2 to launch and have backend volume from ceph

kind of you can use volume types to do this indrectly. end users shoudl generally not be aware if its ceph or an emc san you less you name the volumens tyeps "cpeh" and "emc" but that is a operator choice. you can map the volume type to specific backend using there config file.

...

.Can this be achieved using cinder availability zone implementation or any other way?

I have gone through below link (*section Configure Block Storage scheduler multi back end)*

https://docs.openstack.org/cinder/latest/admin/blockstorage-multi-backend.ht...

well that basically covers what you have to do

your cinder config for lvm emc and ceph might look like this

[DEFAULT] enabled_backends=lvm,emc,ceph

[lvm] volume_group = cinder-volume-1 volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver

[emc] use_multipath_for_image_xfer = true volume_driver = cinder.volume.drivers.emc.emc_smis_fc.EMCSMISFCDriver volume_backend_name = emcfc

[ceph] volume_driver = cinder.volume.drivers.rbd.RBDDriver volume_backend_name = ceph rbd_pool = volumes rbd_ceph_conf = /etc/ceph/ceph.conf rbd_flatten_volume_from_snapshot = false rbd_max_clone_depth = 5 rbd_store_chunk_size = 4 rados_connect_timeout = -1

or you might have 3 diffent config one for each

you then create 3 different volume types and assocatie each with a backend

openstack --os-username admin --os-tenant-name admin volume type create lvm openstack --os-username admin --os-tenant-name admin volume type create emc openstack --os-username admin --os-tenant-name admin volume type create ceph

openstack --os-username admin --os-tenant-name admin volume type set lvm --property volume_backend_name=lvm openstack --os-username admin --os-tenant-name admin volume type set emc --property volume_backend_name=emc openstack --os-username admin --os-tenant-name admin volume type set ceph --property volume_backend_name=ceph

then you can create volumes with those types

openstack volume create --size 1 --type lvm my_lvm_volume openstack volume create --size 1 --type ceph my_ceph_volume

and boot a server with them.

openstack server create --volume my_lvm_volume --volume my_ceph_volume ...

if you have cross az attach disabel in nova and you want all type/backend to be accesable in all AZ you need to deploy a instance of the cinder volume driver for each of the tyeps in each az.

i dont know if that answers your question or not but volume types are the way to requst a specific backend at the api level.

...

Suggestions please ..

Regards, Deepa K R

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Regards, Deepa K R | DevOps Team Lead

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