Chapter 7. Deploying the Shared File Systems service with CephFS-NFS

The CephFS-NFS back end in the Shared File Systems service (manila) is composed of Ceph metadata servers (MDS), the NFS gateway (NFS-Ganesha), and the Red Hat Ceph Storage cluster service components.

The Shared File Systems service CephFS-NFS driver uses NFS-Ganesha to provide NFSv4 protocol access to CephFS shares. The Ceph MDS service maps the directories and file names of the file system to objects that are stored in RADOS clusters. NFS gateways can serve NFS file shares with different storage back ends, such as Ceph. The NFS-Ganesha service runs on the Controller nodes with the Ceph services.

Deployment with an isolated network is optional but recommended. In this scenario, instances are booted with at least two NICs: one NIC connects to the project router and the second NIC connects to the StorageNFS network, which connects directly to NFS-Ganesha. The instance mounts shares by using the NFS protocol. CephFS shares that are hosted on Ceph Object Storage Daemon (OSD) nodes are provided through the NFS gateway.

NFS-Ganesha improves security by preventing user instances from directly accessing the MDS and other Ceph services. Instances do not have direct access to the Ceph daemons.

When you use Red Hat Ceph Storage to provide object and block storage, you require the following services for deployment:

For native CephFS, you also require the Ceph Storage Metadata Service (MDS), and for CephFS-NFS, you require the NFS-Ganesha service as a gateway to native CephFS using the NFS protocol.

NFS-Ganesha runs in its own container that interfaces both to the Ceph public network and to a new isolated network, StorageNFS. If you use the composable network feature of Red Hat OpenStack Platform (RHOSP) director, you can deploy the isolated network and connect it to the Controller nodes. As the cloud administrator, you can configure the network as a Networking (neutron) provider network.

NFS-Ganesha accesses CephFS over the Ceph public network and binds its NFS service using an address on the StorageNFS network.

To access NFS shares, you provision Compute (nova) instances with an additional NIC that connects to the Storage NFS network. Export locations for CephFS shares appear as standard NFS IP:<path> tuples that use the NFS-Ganesha server VIP on the StorageNFS network. The network uses the IP address of the instance to perform access control on the NFS shares.

Networking (neutron) security groups prevent an instance that belongs to project 1 from accessing an instance that belongs to project 2 over the StorageNFS network. Projects share the same CephFS file system, but project data path separation is enforced because instances can access files only under export trees: /path/to/share1/…, /path/to/share2/….

When Red Hat OpenStack Platform (RHOSP) director starts the Red Hat Ceph Storage service daemons, they manage their own high availability (HA) state and, in general, there are multiple instances of these daemons running. By contrast, in this release, only one instance of NFS-Ganesha can serve file shares at a time.

To avoid a single point of failure in the data path for CephFS-NFS shares, NFS-Ganesha runs on a RHOSP Controller node in an active-passive configuration that is managed by a Pacemaker-Corosync cluster. NFS-Ganesha acts across the Controller nodes as a virtual service with a virtual service IP address.

If a Controller node fails or the service on a particular Controller node fails and cannot be recovered on that node, Pacemaker-Corosync starts a new NFS-Ganesha instance on a different Controller node using the same virtual IP address. Existing client mounts are preserved because they use the virtual IP address for the export location of shares.

Using default NFS mount-option settings and NFS 4.1 or later, after a failure, TCP connections are reset and clients reconnect. I/O operations temporarily stop responding during failover, but they do not fail. Application I/O also stops responding but resumes after failover completes.

New connections, new lock states, and so on are refused until after a grace period of up to 90 seconds during which time the server waits for clients to reclaim their locks. NFS-Ganesha keeps a list of the clients and exits the grace period earlier if all clients reclaim their locks.

A typical CephFS-NFS installation in a Red Hat OpenStack Platform (RHOSP) environment includes the following configurations:

The Shared File Systems service provides APIs that allow the projects to request file system shares, which are fulfilled by driver modules. If you use the driver for CephFS, manila.share.drivers.cephfs.driver.CephFSDriver, you can use the Shared File Systems service with a CephFS back end. RHOSP director configures the driver to deploy NFS-Ganesha so that the CephFS shares are presented through the NFS 4.1 protocol.

While preparing your CephFS NFS deployment, you will require the isolated StorageNFS network. You can use director to create this isolated StorageNFS network. For more information, see Configuring overcloud networking in Installing and managing Red Hat OpenStack Platform with director.

Manual configuration options for Shared File Systems service back ends

You can manually configure the Shared File Systems service by editing the node file /etc/manila/manila.conf. However, RHOSP director can override any settings in future overcloud updates.

You can add CephFS-NFS to an externally deployed Ceph Storage cluster, which was not configured by director. Currently, you can only define one CephFS back end in director. For more information, see Integrating an overcloud with Ceph Storage in Integrating the overcloud with an existing Red Hat Ceph Storage Cluster.

The Shared File Systems service (manila), Ceph File System (CephFS), and CephFS-NFS manage shares differently.

The Shared File Systems service provides shares, where a share is an individual file system namespace and a unit of storage with a defined size. Shared file system storage allows multiple clients to connect, read, and write data to any given share, but you must give each client access to the share through the Shared File Systems service access control APIs before they can connect.

CephFS manages a share like a directory with a defined quota and a layout that points to a particular storage pool or namespace. CephFS quotas limit the size of a directory to the size of the share that the Shared File Systems service creates.

You control access to CephFS-NFS shares by specifying the IP address of the client. With CephFS-NFS, file shares are provisioned and accessed through the NFS protocol. The NFS protocol also manages security.

For security, isolate NFS traffic to a separate network when using CephFS-NFS so that the NFS server is accessible only through the isolated network. Deployers can restrict the isolated network to a select group of projects in the cloud. Red Hat OpenStack (RHOSP) director ships with support to deploy a dedicated StorageNFS network.

Before you deploy the overcloud to enable CephFS-NFS for use with the Shared File Systems service, you must create the following:

For more information about creating the isolated network, the VIP, and the custom role, see Configuring overcloud networking in Installing and managing Red Hat OpenStack Platform with director.

When you are ready to deploy your environment, use the openstack overcloud deploy command with the custom environments and roles required to run CephFS with NFS-Ganesha.

The overcloud deploy command has the following options in addition to other required options.

The following example shows an openstack overcloud deploy command with options to deploy CephFS with NFS-Ganesha, a Ceph Storage cluster, and Ceph MDS:

[stack@undercloud ~]$ openstack overcloud deploy \
--templates /usr/share/openstack-tripleo-heat-templates  \
-r /home/stack/roles_data.yaml \
-e /home/stack/templates/overcloud-networks-deployed.yaml\
-e /home/stack/templates/overcloud-vip-deployed.yaml \
-e /home/stack/containers-default-parameters.yaml   \
-e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml   \
-e /home/stack/network-environment.yaml  \
-e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/cephadm.yaml  \
-e /usr/share/openstack-tripleo-heat-templates/environments/cephadm/ceph-mds.yaml  \
-e /usr/share/openstack-tripleo-heat-templates/environments/manila-cephfsganesha-config.yaml

For more information about the openstack overcloud deploy command, see Provisioning and deploying your overcloud in Installing and managing Red Hat OpenStack Platform with director.

The environment file for defining a CephFS-NFS back end, manila-cephfsganesha-config.yaml, is located in the following path of an undercloud node: /usr/share/openstack-tripleo-heat-templates/environments/manila-cephfsganesha-config.yaml.

The manila-cephfsganesha-config.yaml environment file contains settings relevant to the deployment of the Shared File Systems service (manila). The back-end default settings work for most environments. The following example shows the default values that director uses during deployment of the Shared File Systems service:

[stack@undercloud ~]$ cat /usr/share/openstack-tripleo-heat-templates/environments/manila-cephfsganesha-config.yaml
# A Heat environment file which can be used to enable a
# a Manila CephFS-NFS driver backend.
resource_registry:
  OS::TripleO::Services::ManilaApi: ../deployment/manila/manila-api-container-puppet.yaml
  OS::TripleO::Services::ManilaScheduler: ../deployment/manila/manila-scheduler-container-puppet.yaml
  # Only manila-share is pacemaker managed:
  OS::TripleO::Services::ManilaShare: ../deployment/manila/manila-share-pacemaker-puppet.yaml
  OS::TripleO::Services::ManilaBackendCephFs: ../deployment/manila/manila-backend-cephfs.yaml
  # ceph-nfs (ganesha) service is installed and configured by Director
  # but it's still managed by pacemaker
  OS::TripleO::Services::CephNfs: ../deployment/cephadm/ceph-nfs.yaml

parameter_defaults:
  ManilaCephFSBackendName: cephfs 1
  ManilaCephFSDriverHandlesShareServers: false 2
  ManilaCephFSCephFSAuthId: 'manila' 3
  # manila cephfs driver supports either native cephfs backend - 'CEPHFS'
  # (users mount shares directly from ceph cluster), or nfs-ganesha backend -
  # 'NFS' (users mount shares through nfs-ganesha server)
  ManilaCephFSCephFSProtocolHelperType: 'NFS'

The parameter_defaults header signifies the start of the configuration. To override default values set in resource_registry, copy this manila-cephfsganesha-config.yaml environment file to your local environment file directory, /home/stack/templates/, and edit the parameter settings as required by your environment. This includes values set by OS::Tripleo::Services::ManilaBackendCephFs, which sets defaults for a CephFS back end.

For more information about environment files, see Environment files in Installing and managing Red Hat OpenStack Platform with director.