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  • Launchpad Entry: NovaSpec:sheepdog-support
  • Created: 2010-11-15
  • Contributors: Kazutaka Morita, Tomonori Fujita


Add Sheepdog support to Nova instances.

Release Note

Sheepdog is a distributed block storage system for QEMU. This proposes integrating Sheepdog into OpenStack and providing highly available block volumes for VMs like Amazon EBS. The details about Sheepdog are in http://www.osrg.net/sheepdog/.


Current implementation of volumes (iSCSI/AoE with LVM) is not fit for IaaS.

  • the architecture is not scalable in capacity and performance
  • LVM machine could become a SPOF
  • If we take many LVM snapshots, the performance of volumes becomes terrible

User stories

A hosting service provider want to provide block level storage volumes to thousands of users. However, a single LVM machine cannot achieve such a scalability, and a highend storage system is not acceptable from the point of view of cost. Sheepdog solves this problem.




create a new class SheepdogDriver like the following:

class SheepdogDriver(VolumeDriver):
    """Executes commands relating to Sheepdog Volumes"""

    def check_for_setup_error(self):
        """Returns an error if prerequisites aren't met"""
        # TODO: check whether sheepdog is starting or not

    def create_volume(self, volume):
        """Creates a sheepdog volume"""
        yield self._try_execute("qemu-img create sheepdog:%s %s" %
                            (volume['name'], volume['size']))

    def delete_volume(self, volume):
        """Deletes a logical volume"""
        yield self._try_execute("collie vdi delete %s" % volume['name'])

    def ensure_export(self, context, volume):
        """Safely and synchronously recreates an export for a logical volume"""
        # TODO: check whether volume['name'] exists

    def create_export(self, context, volume):
        """Exports the volume"""

    def remove_export(self, context, volume):
        """Removes an export for a logical volume"""

    def discover_volume(self, volume):
        """Discover volume on a remote host"""
        defer.returnValue("sheepdog:%s" % volume['name'])

    def undiscover_volume(self, volume):
        """Undiscover volume on a remote host"""