Open Cloud Day 2018

This year we had the pleasure to organize and host one of Switzerland’s most prestigious cloud events, the OpenCloudDay. On the 30th of May, we welcomed the around 80 participants at the ZHAW School of Engineering in Winterthur for a day rich with technical talks, demos and networking possibilities for Cloud Computing practitioners and experts in Switzerland.

Welcome and introduction to Open Cloud Day 2018

The program of the day started with two opening talks covering very timely topics in the field of Cloud Computing. The first talk, given by Thomas Michael Bohnert from the ICCLab, was a critical view on what many consider as the next evolutionary direction of Cloud Computing, namely Edge Computing. We got the speaker’s perspective on the motivations, the potential obstacles and open issues for this paradigm to definitely break through (or maybe not) as the next Cloud Computing frontier. The second opening talk was given by Sacha Dubois from Red Hat and focused on the potential of Ansible Tower for the automation and management of Hybrid Clouds. After a general discussion on the possibilities offered by Ansible Tower to managing both on-premise and public cloud workloads, a live demo showed how this would work in the practice.

Presentation on Ansible Tower by Red Hat

During the second part of the morning and the first part of the afternoon, two technical sessions were ran in parallel. Several topics were covered as for instance Continuous Delivery, Continuous Deployment and Continuous Integration in the Cloud, and the CNCF activities during the last year, the challenges with the adoption of Web Application Firewall for the DevOps methodology and much more. An insightful presentation was given on the current cloudware technologies and what to expect from future post-clouds systems. Practical experiences were also presented as, for instance, in setting up a Kubernetes cluster, on the use of Ansible for cloud solutions. Also a workshop about the setup of an  oVirt infrastructure for an open source Cloud Management Software was organized in the morning. For a complete program of the technical talks please visit the webpage of the OpenCloudDay.

Attendees during one of the technical presentations

The two final technical talks of the day were given by Niklaus Hofer from Stepping Stone and Jens-Christian Fischer from SWITCH. In the first of the two talks, a presentation was given on the analysis of storage performance for a Ceph cluster. More specifically, the focus was on the comparison between the new backend solution for the Luminous Ceph release, i.e. BlueStore, and the FileStore solution for storing data to disk. Open challenges and further open points of investigation were also given.
The last talk brought up a different point of view regarding all the technical solutions to run a cloud. Based on the experience of SWITCH in running an OpenStack/Ceph based cloud for the Swiss Academic community, the importance of the users’ role in using the technology was put in focus. The user’s perspective is not to be overseen as this puts additional challenges and requirements for solutions to be deployed as the experience of SWITCH clearly highlighted.

The program of the day also offered a total of seven demo presentations on the following topics: Cloud Robotics, Edge Computing, CAB, CNA, Service Tooling, ElasTest, T-Systems solutions.

One of the demos presented by the ICCLab

Storage & Data Analytics – Swiss 2018

On the 24th of May we attended the “Storage & Data Analytics – Swiss 2018” day which was organized at the Seedamm Plaza in Pfäffikon SZ.
Our interest and expertise at the ICCLab for innovative solutions in the area of Cloud Storage motivated us to join the event with the aim to exchange expertise with colleagues from both the industrial and the academic realms.

Welcome and introduction to the day

The program for the event offered a well-balanced mix of keynote speeches from top-experts in the field of storage and data analytics, presentations from specialists and companies actively working in the continuously evolving market, workshops, round-tables, and live demos on specific aspects of interest, and important moments for networking and knowledge exchange with the participants.
Besides the keynotes, the program was organized with four sessions running in parallel. The high number of persons attending the sessions and the stands proposed by the industrial partners for the event witnesses the high interest in the topics in focus. Five major areas of interest were covered: Data Management, Data Analytics, Cloud Storage, Technology and Security. You can find the complete program at the following link https://www.storage-day.ch/

Harald Seipp (IBM) presents Storage in Container-based Cloud Infrastructure

The research and development interests at the ICCLab naturally attracted our interest towards presentations in the area of Cloud Storage and Technology. The first Keynote of the day by Prof. Brinkmann from the University of Mainz, guided us through a classification of Storage with a view on the future of Storage. In the subsequent presentation by IBM, Storage in container-based Cloud Infrastructures was discussed underlying the importance of persistant storage and multi-cloud environments. Of particular interest to us was the presentation given by the company SUSE. Software Defined Storage was discussed as the de-facto Standard for storage in the Cloud, highlighting also the importance of open source based solutions when they presented their Enterprise Storage solution based on Openstack and Ceph. A further interesting analysis on Cloud Storage was later presented by the company Nutanix which introduced their full-stack solution for Storage in the Cloud.

As an icing on the cake, the day was concluded by the insightful keynote given by Moshe Rappaport, Executive Technologist at IBM Research, which guided the audience in the future shedding light on the new disruptive technologies being ahead of us. The future of Storage was also predicted as this is rapidly evolving towards high density data storage applications requiring innovative research and development solutions.

Moshe Rappaport’s insightful keynote on the future of Business and IT from an IBM research perspective

In conclusion, our participation to the “Storage & Data Analytics – Swiss 2018” was well worth the time investment. The event has clearly fulfilled the expectations as an important source of inspiration for our research activities and as an opportunity for networking with experts in the field. We are already looking forward to the next event of this kind!

Deploy Ceph and start using it: end to end tutorial – simple librados client (part 3/3)

(Part 1/3 – Installation – Part 2/3 – troubleshooting)

This part of the tutorial describes how to setup a simple Ceph client using librados (for C++).

The only information that the client requires for the cephx authentication is

  • Endpoint of the monitor node
  • Keyring containing the pre-shared secret (we will use the admin keyring)

Install librados APIs

On Ubuntu, the library is available on the repositories

$ sudo apt-get install librados-dev

Create a client configuration file

This is the file from which librados will read the client configuration.

The content of the file is structured according to this template:

[global]
mon host= <IP address of one of the monitors>
keyring = <path/to/client.admin.keyring>

for example:

[global]
mon host = 192.168.252.10:6789
keyring = ./ceph.client.admin.keyring

The public endpoint of the monitor node can be retrieved with

$ ceph mon stat

The keyring file can be copied from the admin node. No change is needed to this file. The same information that is contained in the file can be retrieved with this command that will also list the client capabilities:

$ ceph auth get client.admin

Connect to the cluster

The following simple client will perform the following operations:

  • Read the configuration file (ceph.conf) from the local directory
  • Get an handle to the cluster and IO context on the “data” pool
  • Create a new object
  • Set an xattr
  • Read the object and xattr back
  • Print the list of pools
  • Print the list of objects in the “data” pool
  • Cleanup
  1. #include <rados/librados.hpp>
  2. #include <string>
  3. #include <list>
  4. int main(int argc, const char **argv)
  5. {
  6.   int ret = 0;
  7.   /*
  8.    * Errors are not checked to avoid pollution.
  9.    * After each Ceph operation:
  10.    * if (ret < 0) error_condition
  11.    * else success
  12.    */
  13.   // Get cluster handle and connect to cluster
  14.   std::string cluster_name(“ceph”);
  15.   std::string user_name(“client.admin”);
  16.   librados::Rados cluster;
  17.   cluster.init2(user_name.c_str(), cluster_name.c_str()0);
  18.   cluster.conf_read_file(“ceph.conf”);
  19.   cluster.connect();
  20.   // IO context
  21.   librados::IoCtx io_ctx;
  22.   std::string pool_name(“data”);
  23.   cluster.ioctx_create(pool_name.c_str(), io_ctx);
  24.   // Write an object synchronously
  25.   librados::bufferlist bl;
  26.   std::string objectId(“hw”);
  27.   std::string objectContent(“Hello World!”);
  28.   bl.append(objectContent);
  29.   io_ctx.write(objectId, bl, objectContent.size()0);
  30.   // Add an xattr to the object.
  31.   librados::bufferlist lang_bl;
  32.   lang_bl.append(“en_US”);
  33.   io_ctx.setxattr(objectId, “lang”, lang_bl);
  34.   // Read the object back asynchronously
  35.   librados::bufferlist read_buf;
  36.   int read_len = 4194304;
  37.   //Create I/O Completion.
  38.   librados::AioCompletion *read_completion =
  39.                                              librados::Rados::aio_create_completion();
  40.   //Send read request.
  41.   io_ctx.aio_read(objectId, read_completion, &read_buf, read_len, 0);
  42.   // Wait for the request to complete, and print content
  43.   read_completion>wait_for_complete();
  44.   read_completion>get_return_value();
  45.   std::cout << “Object name: “ << objectId << \n
  46.             << “Content: “ << read_buf.c_str() << std::endl;
  47.   // Read the xattr.
  48.   librados::bufferlist lang_res;
  49.   io_ctx.getxattr(objectId, “lang”, lang_res);
  50.   std::cout << “Object xattr: “ << lang_res.c_str() << std::endl;
  51.   // Print the list of pools
  52.   std::list<std::string> pools;
  53.   cluster.pool_list(pools);
  54.   std::cout << “List of pools from this cluster handle” << std::endl;
  55.   for (auto pool_id : pools) {
  56.     std::cout << \t << pool_id << std::endl;
  57.   }
  58.   // Print the list of objects
  59.   librados::ObjectIterator oit = io_ctx.objects_begin();
  60.   librados::ObjectIterator oet = io_ctx.objects_end();
  61.   std::cout << “List of objects from this pool” << std::endl;
  62.   for (; oit != oet; oit++) {
  63.     std::cout << \t << oit>first << std::endl;
  64.   }
  65.   // Remove the xattr
  66.   io_ctx.rmxattr(objectId, “lang”);
  67.   // Remove the object.
  68.   io_ctx.remove(objectId);
  69.   // Cleanup
  70.   io_ctx.close();
  71.   cluster.shutdown();
  72.   return 0;
  73. }

Find the pastebin here.

This example can be compiled and executed with

$ g++ client.cpp -lrados -o cephclient
$ ./cephclient

Operate with cluster data from the command line

To quickly verify if an object was written or to remove it, use the following commands (e.g., from the monitor node).

  • List objects in pool data

    $ rados -p data ls
  • Check the location of an object in pool data

    $ ceph osd map data <object name>
  • Remove object from pool data

    $ rados rm <object name> --pool=data

Deploy Ceph and start using it: end to end tutorial – Troubleshooting (part 2/3)

(Part 1/3 – Installation – Part 3/3 – librados client)

It is quite common that after the initial installation, the Ceph cluster reports health warnings. Before using the cluster for storage (e.g., allow clients to access it), a HEALTH_OK state should be reached:

cluster-admin@ceph-mon0:~/ceph-cluster$ ceph health
HEALTH_OK

This part of the tutorial provides some troubleshooting hints that I collected during the setup of my deployments. Other helpful resources are the Ceph IRC channel and mailing lists.

Useful diagnostic commands

A collection of diagnostic commands to check the status of the cluster is listed here. Running these commands is how we can understand that the Ceph cluster is not properly configured.

  1. Ceph status
    $ ceph status

    In this example, the disk for one OSD had been physically removed, so 2 out of 3 OSDs were in and up.

    cluster-admin@ceph-mon0:~/ceph-cluster$ ceph status
        cluster 28f9315e-6c5b-4cdc-9b2e-362e9ecf3509
         health HEALTH_OK
         monmap e1: 1 mons at {ceph-mon0=192.168.0.1:6789/0}, election epoch 1, quorum 0 ceph-mon0
         osdmap e122: 3 osds: 2 up, 2 in
          pgmap v4699: 192 pgs, 3 pools, 0 bytes data, 0 objects
                87692 kB used, 1862 GB / 1862 GB avail
                     192 active+clean
  2. Ceph health
    $ ceph health
    $ ceph health detail
  3. Pools and OSDs configuration and status
    $ ceph osd dump
    $ ceph osd dump --format=json-pretty

    the second version provides much more information, listing all the pools and OSDs and their configuration parameters

  4. Tree of OSDs reflecting the CRUSH map
    $ ceph osd tree

    This is very useful to understand how the cluster is physically organized (e.g., which OSDs are running on which host).

  5. Listing the pools in the cluster
    $ ceph osd lspools

    This is particularly useful to check clients operations (e.g., if new pools were created).

  6. Check the CRUSH rules
    $ ceph osd crush dump --format=json-pretty
  7. List the disks of one node from the admin node
    $ ceph-deploy disk list osd0
  8. Check the logs.
    Log files in /var/log/ceph/ will provide a lot of information for troubleshooting. Each node of the cluster will contain logs about the Ceph components that it runs, so you may need to SSH on different hosts to have a complete diagnosis.

Check your firewall and network configuration

Every node of the Ceph cluster must be able to successfully run

$ ceph status

If this operation times out without giving any results, it is likely that the firewall (or network configuration) is not allowing the nodes to communicate.

Another symptom of this problem is that OSDs cannot be activated, i.e., the ceph-deploy osd activate <args> command will timeout.

Ceph monitor default port is 6789Ceph OSDs and MDS try to get the first available ports starting at 6800.

A typical Ceph cluster might need the following ports:

Mon:  6789
Mds:  6800
Osd1: 6801
Osd2: 6802
Osd3: 6803

Depending on your security requirements, you may want to simply allow any traffic to and from the Ceph cluster nodes.

References: http://comments.gmane.org/gmane.comp.file-systems.ceph.devel/2231

Try restarting first

Without going for fine troubleshootings and log analysis, sometimes (especially after the first installation), I’ve noticed that a simple restart of the Ceph components has helped the transition from a HEALTH_WARN to a HEALTH_OK state.

If some of the OSDs are not in or not up, like in the case below

    cluster 07d28faa-48ae-4356-a8e3-19d5b81e159e
     health HEALTH_WARN 192 pgs incomplete; 192 pgs stuck inactive; 192 pgs stuck unclean; 1/2 in osds are down; clock skew detected on mon.1, mon.2
     monmap e3: 3 mons at {0=192.168.252.10:6789/0,1=192.168.252.11:6789/0,2=192.168.252.12:6789/0}, election epoch 36, quorum 0,1,2 0,1,2
     osdmap e27: 6 osds: 1 up, 2 in
      pgmap v57: 192 pgs, 3 pools, 0 bytes data, 0 objects
            84456 kB used, 7865 MB / 7948 MB avail
                 192 incomplete

try to start the OSD daemons with

# on osd0
$ sudo /etc/init.d/ceph -a start osd0

If the OSDs are in, but PGs are in weird states, like in the example below

cluster 07d28faa-48ae-4356-a8e3-19d5b81e159e
     health HEALTH_WARN 192 pgs degraded; 192 pgs stuck unclean; clock skew detected on mon.1, mon.2
     monmap e3: 3 mons at {0=192.168.252.10:6789/0,1=192.168.252.11:6789/0,2=192.168.252.12:6789/0}, election epoch 36, quorum 0,1,2 0,1,2
     osdmap e34: 6 osds: 6 up, 6 in
      pgmap v71: 192 pgs, 3 pools, 0 bytes data, 0 objects
            235 MB used, 23608 MB / 23844 MB avail
                 128 active+degraded
                  64 active+replay+degraded

try to restart the monitor(s) with

# on mon0
$ sudo /etc/init.d/ceph -a restart mon0

Unfortunately, a simple restart will be the solution in just a few rare cases. More troubleshooting will be required in the majority of the situations.

Unable to find keyring

During the deployment of the monitor nodes (the ceph-deploy <mon> [<mon>] create-initial step), Ceph may complain about missing keyrings:

[ceph_deploy.gatherkeys][WARNIN] Unable to find
/etc/ceph/ceph.client.admin.keyring on ['ceph-server']

If this warning is reported (even if the message is not an error), the Ceph cluster will probably not reach an healthy state.

The solution to this problem is to use exactly the same names for the hostnames (i.e., the output of hostname -s) and the Ceph node names.

This means that the files

  • /etc/hosts
  • /etc/hostname
  • .ssh/config (only for the admin node)

and the result of the command hostname -s, all should have the same names for a certain node.

See also:

 Check that replication requirements can be met

I’ve found that most of my problems with Ceph health were related to wrong (i.e., unfeasible) replication policies.

This is particularly likely to happen in test deployment where one doesn’t care about setting up many OSDs or separating them across different hosts.

Some common pitfalls here may be:

  1. The number of required replicas is higher than the number of OSDs (!!)
  2. CRUSH is instructed to separate replicas across hosts but multiple OSDs are on the same host and there are not enough OSD hosts to satisfy this condition

The visible effect when running diagnostic commands is that PGs will be in wrong statuses.

CASE 1the replication level is such that it cannot be accomplished with the current cluster (e.g., a replica size of 3 with 2 OSDs).

Check the replicated size of pools with

$ ceph osd dump

Adjust the replicated size and min_size, if required, by running

$ ceph osd pool set <pool_name> size <value>
$ ceph osd pool set <pool_name> min_size <value>

CASE 2: the replication policy would require replicas to sit on separate hosts, but OSDs are running within the same hosts

Check what crush_ruleset applies to a certain pool with

$ ceph osd dump --format=json-pretty

In the example below, the pool with id 0 (“data”) is using the crush_ruleset with id 0

"pools": [
        { "pool": 0,
          "pool_name": "data",
          [...]
          "crush_ruleset": 0,  <----
          "object_hash": 2,
          [...]

then check with

$ ceph osd crush dump --format=json-pretty

what crush_ruleset 0 is about.

In the example below, we can observe that this rules says to replicate data by choosing the first available leaf in the CRUSH map, which is of type host.

"rules": [
        { "rule_id": 0,
          "rule_name": "replicated_ruleset",
          "ruleset": 0,
          "type": 1,
          "min_size": 1,
          "max_size": 10,
          "steps": [
                { "op": "take",
                  "item": -1,
                  "item_name": "default"},
                { "op": "chooseleaf_firstn",     <-----------
                  "num": 0,
                  "type": "host"},               <-----------
                { "op": "emit"}]}],

If not enough hosts are available, then the application of this rule will fail.

To allow replicas to be created on different OSDs but possibly on the same host, we need to create a new ruleset:

$ ceph osd crush rule create-simple replicate_within_hosts default osd

After the rule has been created, it should be listed in the output of

$ ceph osd crush dump

from where we can not its id.

The next step is to apply this rule to the pools as required:

$ ceph osd pool set data crush_ruleset <rulesetId>
$ ceph osd pool set metadata crush_ruleset <rulesetId>
$ ceph osd pool set rbd crush_ruleset <rulesetId>

Deploy Ceph and start using it: end to end tutorial – Installation (part 1/3)

Ceph is one of the most interesting distributed storage systems available, with a very active development and a complete set of features that make it a valuable candidate for cloud storage services. This tutorial goes through the required steps (and some related troubleshooting), required to setup a Ceph cluster and access it with a simple client using librados. Please refer to the Ceph documentation for detailed insights on Ceph components.

(Part 2/3 – Troubleshooting – Part 3/3 – librados client)

Assumptions

  • Ceph version: 0.79
  • Installation with ceph-deploy
  • Operating system for the Ceph nodes: Ubuntu 14.04

Cluster architecture

In a minimum Ceph deployment, a Ceph cluster includes one Ceph monitor (MON) and a number of Object Storage Devices (OSD).

Administrative and control operations are issued from an admin node, which must not necessarily be separated from the Ceph cluster (e.g., the monitor node can also act as the admin node). Metadata server nodes (MDS) are required only for Ceph Filesystem (Ceph Block Devices and Ceph Object Storage do not use MDS).

Preparing the storage

WARNING: preparing the storage for Ceph means to delete a disk’s partition table and lose all its data. Proceed only if you know exactly what you are doing!

Ceph will need some physical storage to be used as Object Storage Devices (OSD) and Journal. As the project documentation recommends, for better performance, the Journal should be on a separate drive than the OSD. Ceph supports ext4, btrfs and xfs. I tried setting up clusters with both btrfs and xfs, however I could achieve stable results only with xfs, so I will refer to this latter.

  1. Prepare a GPT partition table (I have observed stability issues when using a dos partition)
    $ sudo parted /dev/sd<x>
    (parted) mklabel gpt
    (parted) mkpart primary xfs 0 ­100%
    (parted) quit

    if parted complains about alignment issues (“Warning: The resulting partition is not properly aligned for best performance”), check this two links to find a solution: 1 and 2.

  2. Format the disk with xfs (you might need to install xfs tools with sudo apt-get install xfsprogs)
    $ sudo mkfs.xfs /dev/sd<x>1
  3. Create a Journal partition (raw/unformatted)
    $ sudo parted /dev/sd<y>
    (parted) mklabel gpt
    (parted) mkpart primary 0 100%

 Install Ceph deploy

The ceph-deploy tool must only be installed on the admin node. Access to the other nodes for configuration purposes will be handled by ceph-deploy over SSH (with keys).

  1. Add Ceph repository to your apt configuration, replace {ceph-stable-release} with the Ceph release name that you want to install (e.g., emperor, firefly, …)
    $ echo deb http://ceph.com/debian-{ceph-stable-release}/ $(lsb_release -sc) main | sudo tee /etc/apt/sources.list.d/ceph.list
  2. Install the trusted key with
    $ wget -q -O- 'https://ceph.com/git/?p=ceph.git;a=blob_plain;f=keys/release.asc' | sudo apt-key add -
  3. If there is no repository for your Ubuntu version, you can try to select the newest one available by manually editing the file /etc/apt/sources.list.d/ceph.list and changing the Ubuntu codename (e.g., trusty -> raring)
    $ deb http://ceph.com/debian-emperor raring main
  4. Install ceph-deploy
    $ sudo apt-get update
    $ sudo apt-get install ceph-deploy

Setup the admin node

Each Ceph node will be setup with an user having passwordless sudo permissions and each node will store the public key of the admin node to allow for passwordless SSH access. With this configuration, ceph-deploy will be able to install and configure every node of the cluster.

NOTE: the hostnames (i.e., the output of hostname -s) must match the Ceph node names!

  1. [optional] Create a dedicated user for cluster administration (this is particularly useful if the admin node is part of the Ceph cluster)
    $ sudo useradd -d /home/cluster-admin -m cluster-admin -s /bin/bash

    then set a password and switch to the new user

    $ sudo passwd cluster-admin
    $ su cluster-admin
  2. Install SSH server on all the cluster nodes (even if a cluster node is also an admin node)
    $ sudo apt-get install openssh-server
  3. Add a ceph user on each Ceph cluster node (even if a cluster node is also an admin node) and give it passwordless sudo permissions
    $ sudo useradd -d /home/ceph -m ceph -s /bin/bash
    $ sudo passwd ceph
    <Enter password>
    $ echo "ceph ALL = (root) NOPASSWD:ALL" | sudo tee /etc/sudoers.d/ceph
    $ sudo chmod 0440 /etc/sudoers.d/ceph
  4. Edit the /etc/hosts file to add mappings to the cluster nodes. Example:
    $ cat /etc/hosts
    127.0.0.1       localhost
    192.168.58.2    mon0
    192.168.58.3    osd0
    192.168.58.4    osd1

    to enable dns resolution with the hosts file, install dnsmasq

    $ sudo apt-get install dnsmasq
  5. Generate a public key for the admin user and install it on every ceph nodes
    $ ssh-keygen
    $ ssh-copy-id ceph@mon0
    $ ssh-copy-id ceph@osd0
    $ ssh-copy-id ceph@osd1
  6. Setup an SSH access configuration by editing the .ssh/config file. Example:
    Host osd0
       Hostname osd0
       User ceph
    Host osd1
       Hostname osd1
       User ceph
    Host mon0
       Hostname mon0
       User ceph
  7. Before proceeding, check that ping and host commands work for each node
    $ ping mon0
    $ ping osd0
    ...
    $ host osd0
    $ host osd1

Setup the cluster

Administration of the cluster is done entirely from the admin node.

  1. Move to a dedicated directory to collect the files that ceph-deploy will generate. This will be the working directory for any further use of ceph-deploy
    $ mkdir ceph-cluster
    $ cd ceph-cluster
  2. Deploy the monitor node(s) – replace mon0 with the list of hostnames of the initial monitor nodes
    $ ceph-deploy new mon0
    [ceph_deploy.cli][INFO  ] Invoked (1.4.0): /usr/bin/ceph-deploy new mon0
    [ceph_deploy.new][DEBUG ] Creating new cluster named ceph
    [ceph_deploy.new][DEBUG ] Resolving host mon0
    [ceph_deploy.new][DEBUG ] Monitor mon0 at 192.168.58.2
    [ceph_deploy.new][INFO  ] making sure passwordless SSH succeeds
    [ceph_deploy.new][DEBUG ] Monitor initial members are ['mon0']
    [ceph_deploy.new][DEBUG ] Monitor addrs are ['192.168.58.2']
    [ceph_deploy.new][DEBUG ] Creating a random mon key...
    [ceph_deploy.new][DEBUG ] Writing initial config to ceph.conf...
    [ceph_deploy.new][DEBUG ] Writing monitor keyring to ceph.mon.keyring...
  3. Add a public network entry in the ceph.conf file if you have separate public and cluster networks (check the network configuration reference)
    public network = {ip-address}/{netmask}
  4. Install ceph in all the nodes of the cluster. Use the --no-adjust-repos option if you are using different apt configurations for ceph. NOTE: you may need to confirm the authenticity of the hosts if your accessing them on SSH for the first time!
    Example (replace mon0 osd0 osd1 with your node names):

    $ ceph-deploy install --no-adjust-repos mon0 osd0 osd1
  5. Create monitor and gather keys
    $ ceph-deploy mon create-initial
  6. The content of the working directory after this step should look like
    cadm@mon0:~/my-cluster$ ls
    ceph.bootstrap-mds.keyring  ceph.bootstrap-osd.keyring  ceph.client.admin.keyring  ceph.conf  ceph.log  ceph.mon.keyring  release.asc

Prepare OSDs and OSD Daemons

When deploying OSDs, consider that a single node can run multiple OSD Daemons and that the journal partition should be on a separate drive than the OSD for better performance.

  1. List disks on a node (replace osd0 with the name of your storage node(s))
    $ ceph-deploy disk list osd0

    This command is also useful for diagnostics: when an OSD is correctly mounted on Ceph, you should see entries similar to this one in the output:

    [ceph-osd1][DEBUG ] /dev/sdb :
    [ceph-osd1][DEBUG ] /dev/sdb1 other, xfs, mounted on /var/lib/ceph/osd/ceph-0
  2. If you haven’t already prepared your storage, or if you want to reformat a partition, use the zap command (WARNING: this will erase the partition)
    $ ceph-deploy disk zap --fs-type xfs osd0:/dev/sd<x>1
  3. Prepare and activate the disks (ceph-deploy also has a create command that should combine this two operations together, but for some reason it was not working for me). In this example, we are using /dev/sd<x>1 as OSD and /dev/sd<y>2 as journal on two different nodes, osd0 and osd1
    $ ceph-deploy osd prepare osd0:/dev/sd<x>1:/dev/sd<y>2 osd1:/dev/sd<x>1:/dev/sd<y>2
    $ ceph-deploy osd activate osd0:/dev/sd<x>1:/dev/sd<y>2 osd1:/dev/sd<x>1:/dev/sd<y>2

Final steps

Now we need to copy the cluster configuration to all nodes and check the operational status of our Ceph deployment.

  1. Copy keys and configuration files, (replace mon0 osd0 osd1 with the name of your Ceph nodes)
    $ ceph-deploy admin mon0 osd0 osd1
  2. Ensure proper permissions for admin keyring
    $ sudo chmod +r /etc/ceph/ceph.client.admin.keyring
  3. Check the Ceph status and health
    $ ceph health
    $ ceph status

    If, at this point, the reported health of your cluster is HEALTH_OK, then most of the work is done. Otherwise, try to check the troubleshooting part of this tutorial.

Revert installation

There are useful commands to purge the Ceph installation and configuration from every node so that one can start over again from a clean state.

This will remove Ceph configuration and keys

ceph-deploy purgedata {ceph-node} [{ceph-node}]
ceph-deploy forgetkeys

This will also remove Ceph packages

ceph-deploy purge {ceph-node} [{ceph-node}]

Before getting a healthy Ceph cluster I had to purge and reinstall many times, cycling between the “Setup the cluster”, “Prepare OSDs and OSD Daemons” and “Final steps” parts multiple times, while removing every warning that ceph-deploy was reporting.