Currently, there are Cinder volume drivers which make use of network-attached storage file systems such as GlusterFS of NFS. The purpose of this blueprint is adding a volume driver supporting SMB based volume backends.
This driver will support Windows Server 2012 (R2 included).
SMB is a widely used protocol, especially in the Microsoft world. Its simplicity along with the big improvements that were introduced in SMB 3 make this type of volume backend a very good alternative.
SMB 3 brings features such as transparent failover, multichanneling using multiple NICs, encrypted communication, and RDMA.
This driver will be backwards compatible, supporting older versions of SMB. It will support using any type of SMB share, including:
- from Scale-Out file servers to basic Windows shares;
- Linux Samba shares;
- vendor specific hardware exporting SMB shares.
This driver will include all the features required by the Juno release. It will have a similar flow with other netowrk attached file system drivers, managing images regarded as volumes while hosted on SMB shares.
It will include support for vhd and vhdx images, which will be hosted on SMB shares. The driver will support password based authentication for mounting the SMB shares.
The snapshot management will be done in a similar way as the Gluster driver, using an additional ”.info” file containing mappings between snapshot ids and their actual paths. This is required as the path can change in time (for example when deleting a snapshot from the chain, the backing file will be changed). Differencing vhd/vhdx images will be used as backing files.
This driver will be based on the SMB volume driver which will be available for Linux distributions.
The driver will periodically ensure that the chosen shares are mounted and also retrieve informations such as free space or total allocated space.
Certain volume related operations will require to be synchronized.
The user will provide a list of SMB shares on which volumes may reside. This list will be placed in a file located at a path configured in the cinder config file. This share list may contain SMB mount options such as flags or credentials.
The config file will also contain the path to the Samba config file. Oversubmit and used space ratios may also be configured.
The user will be able to choose whether to use vhd or vhdx images. The volume type may be parsed as extra spec when creating a volume.
Provide volume related operations support using images hosted on SMB shares.
Override the Linux SMB volume driver methods that are platform specific.
A Cinder CI will be testing the SMB related features.
Using the SMB backend will be documented.