Ceph Cluster Updates to Quickstart Guide

Refer to the ceph quick start guide for the preflight checklist and then storage cluster quick start and make changes mentioned here:

Note: Might not need the initial 2 steps for subscription manager and EPEL repo.

  1. Update yum before updating/ installing other packages. If you don’t get the latest version of ceph-deploy (2.0), use this method to update it to the latest version of 1.5. I got 1.5.37 by default but upgraded it to 1.5.39 to solve a few issues while creating OSDs.

    wget http://download.ceph.com/rpm-luminous/el7/noarch/ceph-deploy-1.5.39-0.noarch.rpm
    rpm -Uvh ceph-deploy-1.5.39-0.noarch.rpm --nodeps
  2. Make sure to update NTP services and change time zone to EST on all nodes including admin.

    ssh user@ceph-server
    sudo useradd -d /home/{username} -m {username}
    sudo passwd {username}
    • Replace “user” with the OS name of node like centos and ceph-server with IP address of that node.
    • Replace “username” with the OS name of node like centos.
  3. Add your user name to sudoers file

    echo "{username} ALL = (root) NOPASSWD:ALL" | sudo tee /etc/sudoers.d/{username}
    sudo chmod 0440 /etc/sudoers.d/{username}

    Replace “username” with OS name on the node like centos.

  4. For the ssh config file:

    Host node1_name
       Hostname node1_ip_address
       User {username}
    Host node2_name
       Hostname node2_ip_address
       User {username}
    Host node3_name
       Hostname node3_ip_address
       User {username}

Replace username with OS name of node like centos.

  1. Either enable firewall on all nodes OR use iptables.

  2. Create new volume in Kaizen for each node (excluding admin) and attach it to the nodes to create a new disk for each node (reflected as /dev/vdb in the path). The volume size might depend on the node size. One of the forums said if the node size is 5-10 GB then the volume should be around 20 GB.

  3. For adding a new node after the cluster has been formed install ceph packages just for that node.

    ceph-deploy install new_node_name

    Transfer the admin-client keyring

    ceph-deploy admin new_node_name
  4. Depending on the version of ceph-deploy the OSD creation commands might differ. The version 2.0 and above is mentioned in the document. For version 1.5.39 the command is:

    ceph-deploy osd create {node_name}:/dev/vdb

    If this doesn’t work, you can split this command into two:- prepare and activate. Do this from the admin node.

    ceph-deploy osd prepare {node_name}:/dev/vdb
    ceph-deploy osd activate {node_name}:/dev/vdb
  5. If you run into an error asking for a few missing keyrings like this:

    2018-03-20 12:16:59.550708 7f916621c700 -1 auth: unable to find a keyring on /etc/ceph/ceph.client.admin.keyring,/etc/ceph/ceph.keyring,/etc/ceph/keyring,/etc/ceph/keyr    ing.bin: (2) No such file or directory
    2018-03-20 12:16:59.550718 7f916621c700 -1 monclient(hunting): ERROR: missing keyring, cannot use cephx for authentication
    2018-03-20 12:16:59.550720 7f916621c700  0 librados: client.admin initialization error (2) No such file or directory
    Error connecting to cluster: ObjectNotFound

    Change permissions for the ceph.client.admin.keyring in all nodes including admin to make them readable/ writable.

    sudo chmod 644 /etc/ceph/ceph.client.admin.keyring

    You are NOT missing/ need any other keyrings apart from the ones already created and listed in the document.

  6. You might run into a health error if you’ve deployed only one OSD and the monitor on the same node. I believe the monitor is just redundant on one node. Make sure to deploy the other OSDs before checking the health status.

  7. You will get a health error/ warning if an OSD goes down. You need to reactivate it. SSH into it and write: sudo ceph-disk activate-all to activate all placement groups. Change keyring permission again for the node and it will be up and running.

  8. To create a new OSD pool: ceph osd pool create {pool-name} pg_num It is mandatory to choose the value of pg_num because it cannot be calculated automatically. Here are a few values commonly used:

    • Less than 5 OSDs set pg_num to 128
    • Between 5 and 10 OSDs set pg_num to 512
    • Between 10 and 50 OSDs set pg_num to 1024
    • If you have more than 50 OSDs, you need to understand the tradeoffs and how to calculate the pg_num value by yourself
    • For calculating pg_num value by yourself please take help of pgcalc tool

To set the object name

ceph osd map {poolname} {object-name}