Persistence Storages

When spawning a user's notebook pod, spawner mounts various types of persistent volumes. They include

• User volume
• Group volume (Project volume)
• Data volume

User volume

User volume stores users' own data. When a user spawns Jupyter server for the first time, the user's PVC is created.

The capacity is determined in the order

1. Use user's specified volumeCapacity
2. If this setting is not defined, use the max userVolumeCapacity of all the groups the user belongs to.
3. If none of the group set the userVolumeCapacity, use the system's defaultUserVolumeCapacity

The storage class is defined in the helm value.

Group volume (Project volume)

A group volume (project volume) stores the data shared by a group. To enable the group volume, the administrator should enable the Shared Volume in the group setting. And the volume is created if it doesn't exist at the very first time of the mount to the group volume.

The storage class is defined in the helm value

primehub:
  sharedVolumeStorageClass: "<rwx-storage-class>"

But in most cases, we use an NFS pvc provisioned by primehub-groupvolume-nfs. The configuration would look like this

primehub:
  sharedVolumeStorageClass: ""
groupvolume:
  storageClass: standard

It means

1. the group volume is manually provisioned
2. the primehub-groupvolume-nfs controller would create an NFS server backed by an RWO pvc
3. the RWO pvc uses a "standard" storage class.

If you didn't specify primehub-group-sc's value ("standard" here) in yaml, it will be set by PRIMEHUB_STORAGE_CLASS env.

Attribute	Description
pvc name	project-<group-name>
volume mount	/project/<group-name>
symbolic link	~/<group-name> -> /project/<group-name>

Data volume

Currently, there are these types of the data volume would be mounted as persistence volume

• pv
• git
• nfs
• hostPath

PV

If the data volume is the type of pv, the data volume is backed by a pvc. The difference comparing to group volume is

• A data volume can be connected to multiple groups; while group volume only belongs to a group
• The connection from data volume to a group can be read-only or read-write
• Can enable an upload server

Under the hood, the storage class is defined in the helm value

groupvolume:
  storageClass: standard

It will create an NFS server backed by an RWO pvc which is similar to group volume.

If you didn't specify a value ("standard" here) in yaml, it will be set by PRIMEHUB_STORAGE_CLASS env.

Attribute	Description
pvc name	dataset-<volume-name>
volume mount	/dataset/<volume-name>
symbolic link	~/datasets/<volume-name> -> /dataset/<volume-name>

The volume-name is the metadata.name in the CRD and the volume-name is spec.volumeName in the CRD.

Git

If the data volume is a type of git, the data volume is backed by a hostpath and periodically pulls the data from a repository. Under the hood, we use gitsync daemonset to sync the data to hostpath

Attribute	Description
hostpath	/home/dataset
volume mount	/gitsync/<volume-name>
symbolic link	~/datasets/<volume-name> -> /dataset/<volume-name>/<volume-name>

Nfs

In this way, the data volume is not backed by a pvc, instead, the volume is a nfs volume

Attribute	Description
nfs	server and path settings
volume mount	/dataset/<volume-name>
symbolic link	~/datasets/<volume-name> -> /dataset/<volume-name>

HostPath

In this way, the data volume is not backed by a pvc, instead, the volume is a hostpath volume

Attribute	Description
hostpath	path setting
volume mount	/dataset/<volume-name>
symbolic link	~/datasets/<volume-name> -> /dataset/<volume-name>

Dataset annotations

Annotation	Description	Default
dataset.primehub.io/mountRoot	The mount path of the pv data volume.	/datasets/
dataset.primehub.io/homeSymlink	Whether a symbolic link to the mountPath is required.	true
dataset.primehub.io/gitSyncHostRoot	The host path to put the gitsync result.	/home/dataset/
dataset.primehub.io/gitSyncRoot	The mount path of the git data volume	/gitsync/
dataset.primehub.io/launchGroupOnly	Mount only when the launching group connects this dataset	false
dataset.primehub.io/uploadServer	Only works in pv type data volume. Create an upload server.	null
dataset.primehub.io/uploadServerAuthSecretName	Only works when an upload server is created. Set http basic auth based on secret.	null

Symbolic links in the home folder

The home folder is mounted by the user volume. However, in order to locate the project volume and data volume easily, we create symbolic links in the home folder.

• Group Volumes: ~/<project-name>
• Data Volumes: ~/datasets/<volume-name>

The symbolic links to a data volume can be removed by setting the annotation dataset.primehub.io/homeSymlink to false

Launch group only

By default, if a user has permissions to access the group volume or a data volume, the spawner would mount it no matter which group the user selects.

But if a group volume or a data volume is configured Launch Group Only to no. The volume is only mounted while the user selects the group which connects to this volume.