Network File System (NFS)

NFS is used as an abstraction layer to allow users to work naturally across file systems. In a cluster setup working across file systems is really important when multiple nodes work on the same data.

Most BiBiGrid users will never really interact consciously with BiBiGrid's underlying NFS, but simply use it.

How To Configure NFS Shares?

When starting an ansible cluster, at least /vol/spool is initialised as an NFS share if the key nfs is True. Further NFS shares can then be configured using configuration's nfsshares key.

Manually Creating NFS Shares

We discourage bypassing BiBiGrid's configuration by creating additional NFS shares manually, because they will not be automatically registered by scheduled workers.

Useful Commands

Summary	Command	Explanation & Comment
List all nfs shares	showmount --exports

NFS commands

See nfs' manpage.

How To Share an Attached Volume

By mounting a volume into a shared directory, volumes can be shared.

Configuration

Let's assume our configuration holds (among others) the keys:

nfs: True
masterMounts:
  - testMount

nfsShares:
  - testShare

Where testMount is an existing, formatted volume with a filesystem type (for example: ext4, ext3, ntfs, ...).

During cluster creation...

1. BiBiGrid sets up the nfsShare /testShare.

2. BiBiGrid attached the volume testMount to our master instance. The volume is not mounted yet.

3. We call the cluster bibigrid-master-ournfsclusterid in the following.

Mounting a Volume Into a Shared Directory

In order to mount a volume into a shared directory, we first need to identify where our volume was attached.

Find Where Volume Has Been Attached

Executing this openstack client command will give us a list of volumes. Most likely it is best run from your local machine.

openstack volume list --os-cloud=openstack

Result:

ID	Name	Status	Size	Attached to
42424242-4242-4242-4242-424242424242	notTestVolume	available	X
42424242-4242-4242-4242-424242424221	testMount	in-use	Y	Attached to bibigrid-master-ournfsclusterid on /dev/vdd

As you can see, the volume testMount was attached to /dev/vdd. We can double-check whether /dev/vdd really exists by executing lsblk or lsblk | grep /dev/vdd on the master.

Mount Volume into Share

As our NFS share is /testShare, we now need to mount dev/vdd into testShare:

sudo mount -t auto /dev/vdd /testShare

The volume testMount is now successfully shared using NFS. Workers can access the volume now by using /testShare, too.