How the GPFS driver works

The GPFS driver enables the use of GPFS in a fashion similar to that of the NFS driver. With the GPFS driver, instances do not actually access a storage device at the block level. Instead, volume backing files are created in a GPFS file system and mapped to instances, which emulate a block device.

	Note
	GPFS software must be installed and running on nodes where Block Storage and Compute services run in the OpenStack environment. A GPFS file system must also be created and mounted on these nodes before starting the cinder-volume service. The details of these GPFS specific steps are covered in GPFS: Concepts, Planning, and Installation Guide and GPFS: Administration and Programming Reference.

Optionally, the Image Service can be configured to store images on a GPFS file system. When a Block Storage volume is created from an image, if both image data and volume data reside in the same GPFS file system, the data from image file is moved efficiently to the volume file using copy-on-write optimization strategy.