CephFS

This article is a draft

This is not a complete article: This is a draft, a work in progress that is intended to be published into an article, which may or may not be ready for inclusion in the main wiki. It should not necessarily be considered factual or authoritative.

User Guide to Provisioning and Deploying CephFS

Introduction

CephFS provides a common filesystem that can be shared amongst multiple openstack vm hosts. Access to the service is granted via requests to cloud@computecanada.ca.

This is a fairly technical procedure that assumes basic Linux skills for creating/editing files, setting permissions and creating mount points. Contact your technical resource for your project for assistance in setting up this service.

Technical Procedure

Request Access to Shares

• If you do not already have a quota for the service you will need to request this through cloud@computecanada.ca.
  • In your request please provide the following:
    • OpenStack Project name
    • Amount of quota required in GB.
    • If more than one share is required, how many are required?

Create Share

1. Create a share in "Shares" under the "Share" menu:
   • Give this a name that identifies your project: project-name-shareName
     • e.g. def-project-shareName
   • Share Protocol = cephfs
   • Size = size you need for this share
   • Share Type = cephfs
   • Availability Zone = nova
   • Do not check "Make visible for all", otherwise the share would be accessible by anyone in every project.
2. Create an Access Rule which generates an Access Key
   • On the "Shares" pane, click on the drop down menu under "Actions" and select "Manage Rules".
   • Create a new rule using the "+Add Rule" button.
     • Access Type = cephx
     • Select "read-write" or "read-only" under "Access Level". You can create multiple rules for either access level if required.
     • Choose a key name in the "Access To" field that describes the key (e.g. def-project-shareName-read-write).
3. Note the Share details:
   • Click on the share.
   • Under "Overview", note the "Path" which you will need later.
   • Under "Access Control", note the "Access Key" which you will need later.
   • Access Keys are approximately 40 characters and end with an "=" sign.
   • If you do not see an Access Key, you probably didn't add an Access Rule with an Access Type = cephx

Configure Host

1. Install required packages

   • Red Hat Family (RHEL, CentOS, Fedora, Scientific Linux, SUSE, etc.):

     1. Install relevant repos for access to ceph client packages:

        ceph-stable (nautilus is current as of this writting)
            https://docs.ceph.com/en/mimic/install/get-packages/
        epel (sudo yum install epel-release)
        
        

     2. Install packages to enable the ceph client on all the VMs you plan on mounting the share:

        libcephfs2
        python-cephfs
        ceph-common
        python-ceph-argparse
        ceph-fuse (only if you intend a fuse mount)
        

     • Debian Family (Debian, Ubuntu, Mint, etc.):

         https://docs.ceph.com/en/mimic/install/get-packages/
     

2. Configure Keys:

   • Create two files in your VM each containing the "Access Key". This key can be found in the rule definition, or in the "Access Rules" section of your share definition.

   • File 1: /etc/ceph/client.fullkey.shareName (e.g. client.fullkey.def-project-shareName-read-write)

     • contents:

       [client.shareName]
           key = AccessKey
       

   • File 2: /etc/ceph/client.keyonly.shareName (e.g client.keyonly.def-project-shareName-read-write)

     • contents:

       AccessKey
       

     • This file only contains the Access Key

   • Own these files correctly to protect the key information:

     • Each file should be own to root

     sudo chown root.root filename
     

     • Each file should be only readable by root

     sudo chmod 600 filename
     

3. Create /etc/ceph/ceph.conf with contents:

   [client]
       client quota = true
       mon host = 10.30.201.3:6789,10.30.202.3:6789,10.30.203.3:6789
   

   • Note: these are the monitors for the Arbutus cluster - if connecting to a different cluster you will need the monitor information specific to that cluster.
     • You can find the monitor information in the Share Details for your share in the "Path" field.

4. Retrieve the connection information from the share page for your connection:

   • Open up the share details by clicking the name of the share in the Shares page.
   • Copy the entire path of the share for mounting the filesystem.

5. Mount the filesystem

   • Create mount point directory somewhere in your host (likely under /mnt/ - e.g. /mnt/ShareName)
   • Via kernel mount using the ceph driver:
     • Syntax: sudo mount -t ceph <path information> <mountPoint> -o name=<shareKeyName>, secretfile=</path/to/keyringfileOnlyFile>
     • sudo mount -t ceph mon1:6789,mon2:6789,mon3:6789:/volumes/_nogroup/share_instance_id
       • e.g sudo mount -t ceph 192.168.17.13:6789,192.168.17.14:6789,192.168.17.15:6789:/volumes/_nogroup/a87b5ef3-b266-4664-a5ed-026cddfdcdb7 /mnt/WebServerShare -o name=def-project-shareName-read-write,secretfile=/etc/ceph/client.keyonly.def-project-sharename-read-write
   • Via ceph-fuse
     • Need to install ceph-fuse
     • Syntax: sudo ceph-fuse <mountPoint> --id=<shareKeyName> --conf=<pathtoCeph.conf> --keyring=<fullKeyringLocation> --client-mountpoint=pathFromShareDetails
       • e.g. sudo ceph-fuse /mnt/WebServerShare --id=def-project-shareName-read-write --conf=/etc/ceph/ceph.conf --keyring=/etc/ceph/client.fullkey.def-project-shareName-read-write --client-mountpoint=/volumes/_nogroup/a87b5ef3-b266-4664-a5ed-026cddfdcdb7

Notes

• A particular share can have more than one user key provisioned for it.
  • This allows a more granular access to the filesystem.
  • For example, if you needed some hosts to only access the filesystem in a read only capacity.
  • If you have multiple keys for a share you can add the extra keys to your host and modify the above mounting procedure.
• This service is not available to hosts outside of the Openstack cluster.