Preflight Checklist

New in version 0.60.

Thank you for trying Ceph! We recommend setting up a ceph-deploy admin node and a 3-node Ceph Storage Cluster to explore the basics of Ceph. This Preflight Checklist will help you prepare a ceph-deploy admin node and three Ceph Nodes (or virtual machines) that will host your Ceph Storage Cluster. Before proceeding any further, see OS Recommendations to verify that you have a supported distribution and version of Linux. When you use a single Linux distribution and version across the cluster, it will make it easier for you to troubleshoot issues that arise in production.

In the descriptions below, Node refers to a single machine.

Ceph Deploy Setup

Add Ceph repositories to the ceph-deploy admin node. Then, install ceph-deploy.

Debian/Ubuntu

For Debian and Ubuntu distributions, perform the following steps:

  1. Add the release key:

    wget -q -O- 'https://download.ceph.com/keys/release.asc' | sudo apt-key add -
  2. Add the Ceph packages to your repository. Replace {ceph-stable-release} with a stable Ceph release (e.g., hammer, jewel, etc.) For example:

    echo deb https://download.ceph.com/debian-{ceph-stable-release}/ $(lsb_release -sc) main | sudo tee /etc/apt/sources.list.d/ceph.list
  3. Update your repository and install ceph-deploy:

    sudo apt-get update && sudo apt-get install ceph-deploy

Note

You can also use the EU mirror eu.ceph.com for downloading your packages. Simply replace http://ceph.com/ by http://eu.ceph.com/

RHEL/CentOS

For CentOS 7, perform the following steps:

  1. On Red Hat Enterprise Linux 7, register the target machine with subscription-manager, verify your subscriptions, and enable the “Extras” repository for package dependencies. For example:

    sudo subscription-manager repos --enable=rhel-7-server-extras-rpms
  2. Install and enable the Extra Packages for Enterprise Linux (EPEL) repository:

    sudo yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

    Please see the EPEL wiki page for more information.

  3. Add the package to your repository. Open a text editor and create a Yellowdog Updater, Modified (YUM) entry. Use the file path /etc/yum.repos.d/ceph.repo. For example:

    sudo vim /etc/yum.repos.d/ceph.repo

    Paste the following example code. Replace {ceph-release} with the recent major release of Ceph (e.g., jewel). Replace {distro} with your Linux distribution (e.g., el7 for CentOS 7). Finally, save the contents to the /etc/yum.repos.d/ceph.repo file.

    [ceph-noarch]
    name=Ceph noarch packages
    baseurl=https://download.ceph.com/rpm-{ceph-release}/{distro}/noarch
    enabled=1
    gpgcheck=1
    type=rpm-md
    gpgkey=https://download.ceph.com/keys/release.asc
  4. Update your repository and install ceph-deploy:

    sudo yum update && sudo yum install ceph-deploy

Note

You can also use the EU mirror eu.ceph.com for downloading your packages. Simply replace http://ceph.com/ by http://eu.ceph.com/

openSUSE

The Ceph project does not currently publish release RPMs for openSUSE, but a stable version of Ceph is included in the default update repository, so installing it is just a matter of:

sudo zypper install ceph
sudo zypper install ceph-deploy

If the distro version is out-of-date, open a bug at https://bugzilla.opensuse.org/index.cgi and possibly try your luck with one of the following repositories:

  1. Hammer:

    https://software.opensuse.org/download.html?project=filesystems%3Aceph%3Ahammer&package=ceph
  2. Jewel:

    https://software.opensuse.org/download.html?project=filesystems%3Aceph%3Ajewel&package=ceph

Ceph Node Setup

The admin node must be have password-less SSH access to Ceph nodes. When ceph-deploy logs in to a Ceph node as a user, that particular user must have passwordless sudo privileges.

Install NTP

We recommend installing NTP on Ceph nodes (especially on Ceph Monitor nodes) to prevent issues arising from clock drift. See Clock for details.

On CentOS / RHEL, execute:

sudo yum install ntp ntpdate ntp-doc

On Debian / Ubuntu, execute:

sudo apt-get install ntp

Ensure that you enable the NTP service. Ensure that each Ceph Node uses the same NTP time server. See NTP for details.

Install SSH Server

For ALL Ceph Nodes perform the following steps:

  1. Install an SSH server (if necessary) on each Ceph Node:

    sudo apt-get install openssh-server

    or:

    sudo yum install openssh-server
  2. Ensure the SSH server is running on ALL Ceph Nodes.

Create a Ceph Deploy User

The ceph-deploy utility must login to a Ceph node as a user that has passwordless sudo privileges, because it needs to install software and configuration files without prompting for passwords.

Recent versions of ceph-deploy support a --username option so you can specify any user that has password-less sudo (including root, although this is NOT recommended). To use ceph-deploy --username {username}, the user you specify must have password-less SSH access to the Ceph node, as ceph-deploy will not prompt you for a password.

We recommend creating a specific user for ceph-deploy on ALL Ceph nodes in the cluster. Please do NOT use “ceph” as the user name. A uniform user name across the cluster may improve ease of use (not required), but you should avoid obvious user names, because hackers typically use them with brute force hacks (e.g., root, admin, {productname}). The following procedure, substituting {username} for the user name you define, describes how to create a user with passwordless sudo.

Note

Starting with the Infernalis release the “ceph” user name is reserved for the Ceph daemons. If the “ceph” user already exists on the Ceph nodes, removing the user must be done before attempting an upgrade.

  1. Create a new user on each Ceph Node.

    ssh user@ceph-server
    sudo useradd -d /home/{username} -m {username}
    sudo passwd {username}
  2. For the new user you added to each Ceph node, ensure that the user has sudo privileges.

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

Enable Password-less SSH

Since ceph-deploy will not prompt for a password, you must generate SSH keys on the admin node and distribute the public key to each Ceph node. ceph-deploy will attempt to generate the SSH keys for initial monitors.

  1. Generate the SSH keys, but do not use sudo or the root user. Leave the passphrase empty:

    ssh-keygen
    
    Generating public/private key pair.
    Enter file in which to save the key (/ceph-admin/.ssh/id_rsa):
    Enter passphrase (empty for no passphrase):
    Enter same passphrase again:
    Your identification has been saved in /ceph-admin/.ssh/id_rsa.
    Your public key has been saved in /ceph-admin/.ssh/id_rsa.pub.
  2. Copy the key to each Ceph Node, replacing {username} with the user name you created with Create a Ceph Deploy User.

    ssh-copy-id {username}@node1
    ssh-copy-id {username}@node2
    ssh-copy-id {username}@node3
  3. (Recommended) Modify the ~/.ssh/config file of your ceph-deploy admin node so that ceph-deploy can log in to Ceph nodes as the user you created without requiring you to specify --username {username} each time you execute ceph-deploy. This has the added benefit of streamlining ssh and scp usage. Replace {username} with the user name you created:

    Host node1
       Hostname node1
       User {username}
    Host node2
       Hostname node2
       User {username}
    Host node3
       Hostname node3
       User {username}

Enable Networking On Bootup

Ceph OSDs peer with each other and report to Ceph Monitors over the network. If networking is off by default, the Ceph cluster cannot come online during bootup until you enable networking.

The default configuration on some distributions (e.g., CentOS) has the networking interface(s) off by default. Ensure that, during boot up, your network interface(s) turn(s) on so that your Ceph daemons can communicate over the network. For example, on Red Hat and CentOS, navigate to /etc/sysconfig/network-scripts and ensure that the ifcfg-{iface} file has ONBOOT set to yes.

Ensure Connectivity

Ensure connectivity using ping with short hostnames (hostname -s). Address hostname resolution issues as necessary.

Note

Hostnames should resolve to a network IP address, not to the loopback IP address (e.g., hostnames should resolve to an IP address other than 127.0.0.1). If you use your admin node as a Ceph node, you should also ensure that it resolves to its hostname and IP address (i.e., not its loopback IP address).

Open Required Ports

Ceph Monitors communicate using port 6789 by default. Ceph OSDs communicate in a port range of 6800:7300 by default. See the Network Configuration Reference for details. Ceph OSDs can use multiple network connections to communicate with clients, monitors, other OSDs for replication, and other OSDs for heartbeats.

On some distributions (e.g., RHEL), the default firewall configuration is fairly strict. You may need to adjust your firewall settings allow inbound requests so that clients in your network can communicate with daemons on your Ceph nodes.

For firewalld on RHEL 7, add the ceph-mon service for Ceph Monitor nodes and the ceph service for Ceph OSDs and MDSs to the public zone and ensure that you make the settings permanent so that they are enabled on reboot.

For example, on monitors:

sudo firewall-cmd --zone=public --add-service=ceph-mon --permanent

and on OSDs and MDSs:

sudo firewall-cmd --zone=public --add-service=ceph --permanent

Once you have finished configuring firewalld with the --permanent flag, you can make the changes live immediately without rebooting:

sudo firewall-cmd --reload

For iptables, add port 6789 for Ceph Monitors and ports 6800:7300 for Ceph OSDs. For example:

sudo iptables -A INPUT -i {iface} -p tcp -s {ip-address}/{netmask} --dport 6789 -j ACCEPT

Once you have finished configuring iptables, ensure that you make the changes persistent on each node so that they will be in effect when your nodes reboot. For example:

/sbin/service iptables save

TTY

On CentOS and RHEL, you may receive an error while trying to execute ceph-deploy commands. If requiretty is set by default on your Ceph nodes, disable it by executing sudo visudo and locate the Defaults requiretty setting. Change it to Defaults:ceph !requiretty or comment it out to ensure that ceph-deploy can connect using the user you created with Create a Ceph Deploy User.

Note

If editing, /etc/sudoers, ensure that you use sudo visudo rather than a text editor.

SELinux

On CentOS and RHEL, SELinux is set to Enforcing by default. To streamline your installation, we recommend setting SELinux to Permissive or disabling it entirely and ensuring that your installation and cluster are working properly before hardening your configuration. To set SELinux to Permissive, execute the following:

sudo setenforce 0

To configure SELinux persistently (recommended if SELinux is an issue), modify the configuration file at /etc/selinux/config.

Priorities/Preferences

Ensure that your package manager has priority/preferences packages installed and enabled. On CentOS, you may need to install EPEL. On RHEL, you may need to enable optional repositories.

sudo yum install yum-plugin-priorities

For example, on RHEL 7 server, execute the following to install yum-plugin-priorities and enable the rhel-7-server-optional-rpms repository:

sudo yum install yum-plugin-priorities --enablerepo=rhel-7-server-optional-rpms

Summary

This completes the Quick Start Preflight. Proceed to the Storage Cluster Quick Start.