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Description

Configures Ceph cluster consisting of 3 CentOS 7 nodes and presents a Rados Block Device (RBD) to a CentOS 7 client.

Tested on Ubuntu 14.04 host.

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Configuration overview

The private 192.168.10.0/24 network is associated with the Vagrant eth1 interfaces. eth0 is used by Vagrant. Vagrant reserves eth0 and this cannot be currently changed (see hashicorp/vagrant#2093).

             ---------------------------------------------------------
             |                     Vagrant HOST                      |
             ---------------------------------------------------------
              |     |                 |     |                 |     |
          eth1| eth0|             eth1| eth0|             eth1| eth0|
192.168.10.100|     |    192.168.10.10|     |    192.168.10.1N|     |
             -----------             -----------             -----------
             | client0 |             | server1 |     ...     | serverN |
             -----------             | OSD     |             | OSD     |
                                     | MON     |             | MON     |
                                     | ADMIN   |             | ADMIN   |
                                     -----------             -----------

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Sample Usage

Install VirtualBox https://www.virtualbox.org/ and Vagrant https://www.vagrantup.com/downloads.html

Start three servers and install Ceph packages with::

    $ git clone https://github.com/marcindulak/vagrant-ceph-rbd-tutorial-centos7.git
    $ cd vagrant-ceph-rbd-tutorial-centos7
    $ vagrant up

The above setup follows loosely the instructions from http://docs.ceph.com/docs/master/rados/deployment/

After having the servers running configure a basic Ceph installation. Although the documentation does not recommend comingling monitors and OSDs on the same host, this is what is done below. The commands are executed as ceph-admin user on only one server (server0 here, though all the servers in this setup are equivalent)::

• create a cluster:

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy new server{0,1,2}'"
  

• edit the ~ceph/ceph.conf generated by the above command to define the public and cluster Ceph networks for the cluster and reduce the OSD journal size to the size of the used block device (/dev/sdc):

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'echo public_network = 192.168.10.0/24 >> ceph.conf'"
        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'echo cluster_network = 192.168.10.0/24 >> ceph.conf'"
        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'echo [osd] >> ceph.conf'"
        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'echo osd_journal_size = 0 >> ceph.conf'"
  

  The reduction of the journal size is done for the purpose of this setup. Normally you may increase the default journal size. In a production setup the public and cluster networks should be different, the cluster network being a "high" performance one. See http://docs.ceph.com/docs/master/rados/configuration/network-config-ref/

• add monitors (MONs)::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy mon create server{0,1,2}'"
        $ sleep 30  # wait for the monitors for form quorum
  

• gather keys::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy gatherkeys server0'"
  

• synchronize /etc/ceph/ceph.conf and keys on all the admin (ADMIN) servers::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy admin server{0,1,2}'"
  

• list the available disks::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy disk list server{0,1,2}'"
  

• zap the /dev/sdb disks (delete the partition table)::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy disk zap server0:sdb server1:sdb server2:sdb'"
  

• prepare the OSDs (Object Storage Daemon)::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy osd prepare server0:sdb:/dev/sdc server1:sdb:/dev/sdc server2:sdb:/dev/sdc'"
  

• activate the OSDs::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy osd activate server0:/dev/sdb1:/dev/sdc server1:/dev/sdb1:/dev/sdc server2:/dev/sdb1:/dev/sdc'"
  

• modify the permissions for ceph.client.admin.keyring::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'sudo chmod +r /etc/ceph/ceph.client.admin.keyring'"
        $ vagrant ssh server1 -c "sudo su - ceph-admin -c 'sudo chmod +r /etc/ceph/ceph.client.admin.keyring'"
        $ vagrant ssh server2 -c "sudo su - ceph-admin -c 'sudo chmod +r /etc/ceph/ceph.client.admin.keyring'"
  

• check some aspects of the cluster status from all the admin servers::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph health'"
        $ vagrant ssh server1 -c "sudo su - ceph-admin -c 'ceph status'"
        $ vagrant ssh server2 -c "sudo su - ceph-admin -c 'ceph df'"
  

  See http://docs.ceph.com/docs/master/rados/operations/monitoring/ for more information.

When an OSD server goes down Ceph will adjust the status of the cluster::

        $ vagrant ssh server1 -c "sudo su - -c 'shutdown -h now'"
        $ sleep 30
        $ vagrant ssh server2 -c "sudo su - ceph-admin -c 'ceph status'"
        $ vagrant up server1
        $ sleep 30
        $ vagrant ssh server1 -c "sudo su - ceph-admin -c 'ceph status'"

The cluster should report now HEALTH_OK.

A Ceph cluster offers object storage, block device and filesystem. Here we create a Ceph block device, called RBD (Rados Block Device), and mount it on a client. See http://docs.ceph.com/docs/master/start/quick-rbd/ for more information about RBD::

• from an ADMIN node install Ceph on the client::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy install --release jewel client0'"
  

• copy /etc/ceph/ceph.conf and keys to the client::

        $ vagrant ssh server0 -c "sudo su - ceph-admin -c 'ceph-deploy admin client0'"
  

• create a 128MB block device image rbd0::

        $ vagrant ssh client0 -c "sudo su - ceph-admin -c 'sudo chmod +r /etc/ceph/ceph.client.admin.keyring'"
        $ vagrant ssh client0 -c "sudo su - ceph-admin -c 'rbd create rbd0 --size 128 -m server0,server1,server2 -k /etc/ceph/ceph.client.admin.keyring'"
  

• map the image to the block device::

        $ vagrant ssh client0 -c "sudo su - ceph-admin -c 'sudo rbd map rbd0 --name client.admin -m server0,server1,server2 -k /etc/ceph/ceph.client.admin.keyring'"
  

• create xfs filesystem and mount the device on the client::

        $ vagrant ssh client0 -c "sudo su - -c 'mkfs.xfs -L rbd0 /dev/rbd0'"
        $ vagrant ssh client0 -c "sudo su - -c 'mkdir /mnt/rbd0'"
        $ vagrant ssh client0 -c "sudo su - -c 'mount /dev/rbd0 /mnt/rbd0'"
  

When done, destroy the test machines with::

    $ vagrant destroy -f

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Dependencies

None

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License

BSD 2-clause

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Todo

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Problems

1. Sat Apr 30 11:14:01 CEST 2016 http://lists.ceph.com/pipermail/ceph-users-ceph.com/2015-December/006780.html

    INFO:ceph-disk:Running command: /usr/bin/udevadm settle --timeout=600
    INFO:ceph-disk:Running command: /sbin/partprobe /dev/sdc
    DEBUG:ceph-disk:partprobe /dev/sdc failed : Error: Error informing the kernel about modifications to partition /dev/sdc1 -- Device or resource busy.  This means Linux won't know about any changes you made to /dev/sdc1 until you reboot -- so you shouldn't mount it or use it in any way before rebooting.
    Error: Failed to add partition 1 (Device or resource busy)
    ...
    Failed to execute command: /usr/sbin/ceph-disk -v prepare --cluster ceph --fs-type xfs -- /dev/sdb /dev/sdc