Open Stack

Hi, all:
	I meet a requirement in my OpenStack environment which initially uses one LVMISCSI backend. Along with the usage, the storage is insufficient, so I want to add a NFS backend to the exists Cinder. 

	There is only a single Cinder-volume in environment, so I need to configure the Cinder to use "multi-backend", which means the initial LVMISCSI storage and the new added NFS storage are both used as the backend. However, the existing volume on initial LVMISCSI backend will not be handled normally after using multi-backend, because the "host" of the exists volume will be thought down. 

	I know that the "migrate" and "retype" APIs aim to handle the "backend capacity expansion", however, each of them can't used for this situation. 

	I think the use case above is common in production environment. Is there some existing method can achieve it ? Currently, I manually updated the "host" value of the existing volumes in database, and the existing volumes can then be handled normally.

	Thanks.

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zhangleiqiang (Trump)

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