Enable LVM2 filtering on overcloud nodes

While by default the overcloud image will not use LVM2 volumes, it is possible that with some Cinder backends, for example remote iSCSI or FC, the remote LUNs hosting OpenStack volumes will be visible on the nodes hosting cinder-volume or nova-compute containers.

In that case, should the OpenStack guest create LVM2 volumes inside its additional disks, those volumes will be scanned by the LVM2 tools installed on the hosting node.

To prevent that, it is possible to configure an LVM2 global_filter when deploying or updating the overcloud. The feature is, by default, disabled and can be enabled passing LVMFilterEnabled: true in a Heat environment file.

When enabled, a global_filter will be computed from the list of physical devices hosting active LVM2 volumes. This list can be extended further, manually, listing any additional block device via LVMFilterAllowlist parameter, which supports regexp. A deny list can be configured as well, via LVMFilterDenylist parameter; it defaults to [‘.*’] so that any block device which isn’t in the allow list will be ignored by the LVM2 tools by default.

Any of the template parameters can be set per-role; for example, to enable the feature only on Compute nodes and add /dev/sdb to the deny list use:

$ cat ~/environment.yaml
    LVMFilterEnabled: true
      - /dev/sdb

Then add the following argument to your openstack overcloud deploy command:

-e environment.yaml