OpenStack NFS Driver Configuration with CloudByte NFS volume

[ OPENSTACK SETUP ]
June 5th, 2016

Introduction

The Network File System (NFS) is a distributed file system protocol originally developed by Sun Microsystems in 1984. An NFS server exports one or more of its file systems, known as shares. An NFS client can mount these exported shares on its own file system. You can perform file actions on this mounted remote file system as if the file system were local.

NFS driver notes

  • cinder-volume manages the mounting of the NFS shares as well as volume creation on the shares. Keep this in mind when planning your OpenStack architecture. If you have one master NFS server, it might make sense to only have one cinder-volume service to handle all requests to that NFS server. However, if that single server is unable to handle all requests, more than one cinder-volume service is needed as well as potentially more than one NFS server.

  • Because data is stored in a file and not actually on a block storage device, you might not see the same IO performance as you would with a traditional block storage driver. Please test accordingly.

  • Despite possible IO performance loss, having volume data stored in a file might be beneficial. For example, backing up volumes can be as easy as copying the volume files.

Options supported by OpenStack NFS driver

The following options are supported in OpenStack NFS driver:

  • nfs_mount_attempts = 3
    • (IntOpt) The number of attempts to mount nfs shares before raising an error. At least one attempt will be made to mount an nfs share, regardless of the value specified.
  • nfs_mount_options = None
    • (StrOpt) Mount options passed to the nfs client. See section of the nfs man page for details.
  • nfs_mount_point_base = $state_path/mnt
    • (StrOpt) Base dir containing mount points for nfs shares.
  • nfs_oversub_ratio = 1.0
    • (FloatOpt) This will compare the allocated to available space on the volume destination. If the ratio exceeds this number, the destination will no longer be valid.
  • nfs_shares_config = /etc/cinder/NFS_SHARE_INFO_FILE
    • (StrOpt) File with the list of available nfs shares
  • nfs_sparsed_volumes = True
    • (BoolOpt) Create volumes as sparsed files which take no space.If set to False volume is created as regular file.In such case volume creation takes a lot of time.
  • nfs_used_ratio = 0.95
    • (FloatOpt) Percent of ACTUAL usage of the underlying volume before no new volumes can be allocated to the volume destination.
  • nfs_mount_options = vers = 3
    • (IntOpt) Version to be used for the NFS volume.

Configuration steps

In order to configure the CloudByte NFS volume against OpenStack NFS driver we need to create and discover the NFS volume from CloudByte first:

  • Firstly create a NFS volume in CloudByte ElastiStor with some good specifictions. For eg, 20 GB.
  • Set the NFS client configuration so that it can point to OpenStack setup machine.
  • Now go to the OpenStack setup and run the showmount -e VSM_IP command to see the NFS export list. (It should show the NFS volume we created)

After the creation and discovery of NFS volume is done proceed wit the following steps to use this volume with OpenStack NFS driver:

  • Create a file , lets say /etc/cinder/cb_nfs_shares, and insert the NFS volume details.

    For eg : 172.16.19.20:/ACC1TEST
  • Now we need to add a new backend in cinder.conf that will point to OpenStack NFS driver.

  • It will also use the cb_nfs_shares to access the NFS volume form CloudByte.

    # vi /etc/cinder/cinder.conf
  
[DEFAULT]
default_volume_type = cb-nfs
enabled_backends = cloudbyte-nfs
  
[cloudbyte-nfs]
nfs_shares_config = /etc/cinder/cb_nfs_shares
volume_driver = cinder.volume.drivers.nfs.NfsDriver
volume_backend_name = cloudbyte-nfs
nfs_mount_options= vers = 3
nfs_mount_point_base = $state_path/mnt
  • Now restart the cinder-volume service and you are good to go.

Abhishek Shrivastava