root disk for instance

Eugen Block eblock at nde.ag
Thu Jul 11 09:53:26 UTC 2019


Hi,

it's always glance that serves the images, it just depends on how you  
decide to create the instance, ephemeral or persistent disks. You can  
find more information about storage concepts in [1].

If I'm not completely wrong, since Newton release the default in the  
Horizon settings is to create an instance from volume, so it would be  
a persistent disk managed by cinder (the volume persists after the  
instance has been deleted, this is also configurable). The image is  
downloaded from glance into a volume on your volume server.

If you change the Horizon behavior or if you launch an instance from  
the cli you'd get an ephemeral disk by nova, depending on your storage  
backend this would be a local copy of the image on the compute node(s)  
or something related in your storage backend, e.g. an rbd object in  
ceph.

Does this clear it up a bit?

Regards,
Eugen

[1]  
https://docs.openstack.org/arch-design/design-storage/design-storage-concepts.html


Zitat von Jyoti Dahiwele <jyotishri403 at gmail.com>:

> Dear Team,
>
> Please clear me my following doubts.
> When I use image from source option  and mini flavor to create an instace,
> from which storage pool instance will get root disk ? From cinder or glance?






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