NFS¶
CephFS namespaces can be exported over NFS protocol using the NFS-Ganesha NFS server.
Requirements¶
Ceph file system (preferably latest stable luminous or higher versions)
In the NFS server host machine, ‘libcephfs2’ (preferably latest stable luminous or higher), ‘nfs-ganesha’ and ‘nfs-ganesha-ceph’ packages (latest ganesha v2.5 stable or higher versions)
NFS-Ganesha server host connected to the Ceph public network
Configuring NFS-Ganesha to export CephFS¶
NFS-Ganesha provides a File System Abstraction Layer (FSAL) to plug in different storage backends. FSAL_CEPH is the plugin FSAL for CephFS. For each NFS-Ganesha export, FSAL_CEPH uses a libcephfs client, user-space CephFS client, to mount the CephFS path that NFS-Ganesha exports.
Setting up NFS-Ganesha with CephFS, involves setting up NFS-Ganesha’s configuration file, and also setting up a Ceph configuration file and cephx access credentials for the Ceph clients created by NFS-Ganesha to access CephFS.
NFS-Ganesha configuration¶
A sample ganesha.conf configured with FSAL_CEPH can be found here, https://github.com/nfs-ganesha/nfs-ganesha/blob/next/src/config_samples/ceph.conf. It is suitable for a standalone NFS-Ganesha server, or an active/passive configuration of NFS-Ganesha servers managed by some sort of clustering software (e.g., Pacemaker). Important details about the options are added as comments in the sample conf. There are options to do the following:
minimize Ganesha caching wherever possible since the libcephfs clients (of FSAL_CEPH) also cache aggressively
read from Ganesha config files stored in RADOS objects
store client recovery data in RADOS OMAP key-value interface
mandate NFSv4.1+ access
enable read delegations (need at least v13.0.1 ‘libcephfs2’ package and v2.6.0 stable ‘nfs-ganesha’ and ‘nfs-ganesha-ceph’ packages)
Configuration for libcephfs clients¶
Required ceph.conf for libcephfs clients includes:
a [client] section with
mon_hostoption set to let the clients connect to the Ceph cluster’s monitors, usually generated viaceph config generate-minimal-conf, e.g.,[global] mon host = [v2:192.168.1.7:3300,v1:192.168.1.7:6789], [v2:192.168.1.8:3300,v1:192.168.1.8:6789], [v2:192.168.1.9:3300,v1:192.168.1.9:6789]
Mount using NFSv4 clients¶
It is preferred to mount the NFS-Ganesha exports using NFSv4.1+ protocols to get the benefit of sessions.
Conventions for mounting NFS resources are platform-specific. The following conventions work on Linux and some Unix platforms:
From the command line:
mount -t nfs -o nfsvers=4.1,proto=tcp <ganesha-host-name>:<ganesha-pseudo-path> <mount-point>
Current limitations¶
Per running ganesha daemon, FSAL_CEPH can only export one Ceph file system although multiple directories in a Ceph file system may be exported.
Exporting over NFS clusters deployed using rook¶
This tutorial assumes you have a kubernetes cluster deployed. If not minikube can be used to setup a single node cluster. In this tutorial minikube is used.
Note
Configuration of this tutorial should not be used in a a real production cluster. For the purpose of simplification, the security aspects of Ceph are overlooked in this setup.
Rook Setup And Cluster Deployment¶
Clone the rook repository:
git clone https://github.com/rook/rook.git
Deploy the rook operator:
cd cluster/examples/kubernetes/ceph
kubectl create -f common.yaml
kubectl create -f operator.yaml
Note
Nautilus release or latest Ceph image should be used.
Before proceding check if the pods are running:
kubectl -n rook-ceph get pod
Note
For troubleshooting on any pod use:
kubectl describe -n rook-ceph pod <pod-name>
If using minikube cluster change the dataDirHostPath to /data/rook in cluster-test.yaml file. This is to make sure data persists across reboots.
Deploy the ceph cluster:
kubectl create -f cluster-test.yaml
To interact with Ceph Daemons, let’s deploy toolbox:
kubectl create -f ./toolbox.yaml
Exec into the rook-ceph-tools pod:
kubectl -n rook-ceph exec -it $(kubectl -n rook-ceph get pod -l "app=rook-ceph-tools" -o jsonpath='{.items[0].metadata.name}') bash
Check if you have one Ceph monitor, manager, OSD running and cluster is healthy:
[root@minikube /]# ceph -s
cluster:
id: 3a30f44c-a9ce-4c26-9f25-cc6fd23128d0
health: HEALTH_OK
services:
mon: 1 daemons, quorum a (age 14m)
mgr: a(active, since 13m)
osd: 1 osds: 1 up (since 13m), 1 in (since 13m)
data:
pools: 0 pools, 0 pgs
objects: 0 objects, 0 B
usage: 5.0 GiB used, 11 GiB / 16 GiB avail
pgs:
Note
Single monitor should never be used in real production deployment. As it can cause single point of failure.
Create a Ceph File System¶
Using ceph-mgr volumes module, we will create a ceph file system:
[root@minikube /]# ceph fs volume create myfs
By default replicated size for OSD is 3. Since we are using only one OSD. It can cause error. Let’s fix this up by setting replicated size to 1.:
[root@minikube /]# ceph osd pool set cephfs.myfs.meta size 1
[root@minikube /]# ceph osd pool set cephfs.myfs.data size 1
Note
The replicated size should never be less than 3 in real production deployment.
Check Cluster status again:
[root@minikube /]# ceph -s
cluster:
id: 3a30f44c-a9ce-4c26-9f25-cc6fd23128d0
health: HEALTH_OK
services:
mon: 1 daemons, quorum a (age 27m)
mgr: a(active, since 27m)
mds: myfs:1 {0=myfs-a=up:active} 1 up:standby-replay
osd: 1 osds: 1 up (since 56m), 1 in (since 56m)
data:
pools: 2 pools, 24 pgs
objects: 22 objects, 2.2 KiB
usage: 5.1 GiB used, 11 GiB / 16 GiB avail
pgs: 24 active+clean
io:
client: 639 B/s rd, 1 op/s rd, 0 op/s wr
Create a NFS-Ganesha Server Cluster¶
Add Storage for NFS-Ganesha Servers to prevent recovery conflicts:
[root@minikube /]# ceph osd pool create nfs-ganesha 64
pool 'nfs-ganesha' created
[root@minikube /]# ceph osd pool set nfs-ganesha size 1
[root@minikube /]# ceph orchestrator nfs add mynfs nfs-ganesha ganesha
Here we have created a NFS-Ganesha cluster called “mynfs” in “ganesha” namespace with “nfs-ganesha” OSD pool.
Scale out NFS-Ganesha cluster:
[root@minikube /]# ceph orchestrator nfs update mynfs 2
Configure NFS-Ganesha Exports¶
Initially rook creates ClusterIP service for the dashboard. With this service type, only the pods in same kubernetes cluster can access it.
Expose Ceph Dashboard port:
kubectl patch service -n rook-ceph -p '{"spec":{"type": "NodePort"}}' rook-ceph-mgr-dashboard
kubectl get service -n rook-ceph rook-ceph-mgr-dashboard
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
rook-ceph-mgr-dashboard NodePort 10.108.183.148 <none> 8443:31727/TCP 117m
This makes the dashboard reachable outside kubernetes cluster and the service type is changed to NodePort service.
Create JSON file for dashboard:
$ cat ~/export.json
{
"cluster_id": "mynfs",
"path": "/",
"fsal": {"name": "CEPH", "user_id":"admin", "fs_name": "myfs", "sec_label_xattr": null},
"pseudo": "/cephfs",
"tag": null,
"access_type": "RW",
"squash": "no_root_squash",
"protocols": [4],
"transports": ["TCP"],
"security_label": true,
"daemons": ["mynfs.a", "mynfs.b"],
"clients": []
}
Note
Don’t use this JSON file for real production deployment. As here the ganesha servers are given client-admin access rights.
We need to download and run this script to pass the JSON file contents. Dashboard creates NFS-Ganesha export file based on this JSON file.:
./run-backend-rook-api-request.sh POST /api/nfs-ganesha/export "$(cat <json-file-path>)"
Expose the NFS Servers:
kubectl patch service -n rook-ceph -p '{"spec":{"type": "NodePort"}}' rook-ceph-nfs-mynfs-a
kubectl patch service -n rook-ceph -p '{"spec":{"type": "NodePort"}}' rook-ceph-nfs-mynfs-b
kubectl get services -n rook-ceph rook-ceph-nfs-mynfs-a rook-ceph-nfs-mynfs-b
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
rook-ceph-nfs-mynfs-a NodePort 10.101.186.111 <none> 2049:31013/TCP 72m
rook-ceph-nfs-mynfs-b NodePort 10.99.216.92 <none> 2049:31587/TCP 63m
Note
Ports are chosen at random by Kubernetes from a certain range. Specific port number can be added to nodePort field in spec.
Testing access to NFS Servers¶
Open a root shell on the host and mount one of the NFS servers:
mkdir -p /mnt/rook
mount -t nfs -o port=31013 $(minikube ip):/cephfs /mnt/rook
Normal file operations can be performed on /mnt/rook if the mount is successful.
Note
If minikube is used then VM host is the only client for the servers. In a real kubernetes cluster, multiple hosts can be used as clients, only when kubernetes cluster node IP addresses are accessible to them.
