As an administrative user, you have some control over which volume back end your volumes reside on. You can specify affinity or anti-affinity between two volumes. Affinity between volumes means that they are stored on the same back end, whereas anti-affinity means that they are stored on different back ends.
For information on how to set up multiple back ends for Cinder, refer to Configure multiple-storage back ends.
Create a new volume on the same back end as Volume_A:
$ cinder create --hint same_host=Volume_A-UUID SIZE
Create a new volume on a different back end than Volume_A:
$ cinder create --hint different_host=Volume_A-UUID SIZE
Create a new volume on the same back end as Volume_A and Volume_B:
$ cinder create --hint same_host=Volume_A-UUID --hint same_host=Volume_B-UUID SIZE
Or:
$ cinder create --hint same_host="[Volume_A-UUID, Volume_B-UUID]" SIZE
Create a new volume on a different back end than both Volume_A and Volume_B:
$ cinder create --hint different_host=Volume_A-UUID --hint different_host=Volume_B-UUID SIZE
Or:
$ cinder create --hint different_host="[Volume_A-UUID, Volume_B-UUID]" SIZE
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