From 7da45d65be36d36b880cc55c5036e96c24b53f00 Mon Sep 17 00:00:00 2001 From: Qiaowei Ren Date: Thu, 1 Mar 2018 14:38:11 +0800 Subject: remove ceph code This patch removes initial ceph code, due to license issue. Change-Id: I092d44f601cdf34aed92300fe13214925563081c Signed-off-by: Qiaowei Ren --- src/ceph/doc/dev/index.rst | 1558 -------------------------------------------- 1 file changed, 1558 deletions(-) delete mode 100644 src/ceph/doc/dev/index.rst (limited to 'src/ceph/doc/dev/index.rst') diff --git a/src/ceph/doc/dev/index.rst b/src/ceph/doc/dev/index.rst deleted file mode 100644 index b76f2f2..0000000 --- a/src/ceph/doc/dev/index.rst +++ /dev/null @@ -1,1558 +0,0 @@ -============================================ -Contributing to Ceph: A Guide for Developers -============================================ - -:Author: Loic Dachary -:Author: Nathan Cutler -:License: Creative Commons Attribution-ShareAlike (CC BY-SA) - -.. note:: The old (pre-2016) developer documentation has been moved to :doc:`/dev/index-old`. - -.. contents:: - :depth: 3 - -Introduction -============ - -This guide has two aims. First, it should lower the barrier to entry for -software developers who wish to get involved in the Ceph project. Second, -it should serve as a reference for Ceph developers. - -We assume that readers are already familiar with Ceph (the distributed -object store and file system designed to provide excellent performance, -reliability and scalability). If not, please refer to the `project website`_ -and especially the `publications list`_. - -.. _`project website`: http://ceph.com -.. _`publications list`: https://ceph.com/resources/publications/ - -Since this document is to be consumed by developers, who are assumed to -have Internet access, topics covered elsewhere, either within the Ceph -documentation or elsewhere on the web, are treated by linking. If you -notice that a link is broken or if you know of a better link, please -`report it as a bug`_. - -.. _`report it as a bug`: http://tracker.ceph.com/projects/ceph/issues/new - -Essentials (tl;dr) -================== - -This chapter presents essential information that every Ceph developer needs -to know. - -Leads ------ - -The Ceph project is led by Sage Weil. In addition, each major project -component has its own lead. The following table shows all the leads and -their nicks on `GitHub`_: - -.. _github: https://github.com/ - -========= ================ ============= -Scope Lead GitHub nick -========= ================ ============= -Ceph Sage Weil liewegas -RADOS Samuel Just athanatos -RGW Yehuda Sadeh yehudasa -RBD Jason Dillaman dillaman -CephFS Patrick Donnelly batrick -Build/Ops Ken Dreyer ktdreyer -========= ================ ============= - -The Ceph-specific acronyms in the table are explained in -:doc:`/architecture`. - -History -------- - -See the `History chapter of the Wikipedia article`_. - -.. _`History chapter of the Wikipedia article`: https://en.wikipedia.org/wiki/Ceph_%28software%29#History - -Licensing ---------- - -Ceph is free software. - -Unless stated otherwise, the Ceph source code is distributed under the terms of -the LGPL2.1. For full details, see `the file COPYING in the top-level -directory of the source-code tree`_. - -.. _`the file COPYING in the top-level directory of the source-code tree`: - https://github.com/ceph/ceph/blob/master/COPYING - -Source code repositories ------------------------- - -The source code of Ceph lives on `GitHub`_ in a number of repositories below -the `Ceph "organization"`_. - -.. _`Ceph "organization"`: https://github.com/ceph - -To make a meaningful contribution to the project as a developer, a working -knowledge of git_ is essential. - -.. _git: https://git-scm.com/documentation - -Although the `Ceph "organization"`_ includes several software repositories, -this document covers only one: https://github.com/ceph/ceph. - -Redmine issue tracker ---------------------- - -Although `GitHub`_ is used for code, Ceph-related issues (Bugs, Features, -Backports, Documentation, etc.) are tracked at http://tracker.ceph.com, -which is powered by `Redmine`_. - -.. _Redmine: http://www.redmine.org - -The tracker has a Ceph project with a number of subprojects loosely -corresponding to the various architectural components (see -:doc:`/architecture`). - -Mere `registration`_ in the tracker automatically grants permissions -sufficient to open new issues and comment on existing ones. - -.. _registration: http://tracker.ceph.com/account/register - -To report a bug or propose a new feature, `jump to the Ceph project`_ and -click on `New issue`_. - -.. _`jump to the Ceph project`: http://tracker.ceph.com/projects/ceph -.. _`New issue`: http://tracker.ceph.com/projects/ceph/issues/new - -Mailing list ------------- - -Ceph development email discussions take place on the mailing list -``ceph-devel@vger.kernel.org``. The list is open to all. Subscribe by -sending a message to ``majordomo@vger.kernel.org`` with the line: :: - - subscribe ceph-devel - -in the body of the message. - -There are also `other Ceph-related mailing lists`_. - -.. _`other Ceph-related mailing lists`: https://ceph.com/irc/ - -IRC ---- - -In addition to mailing lists, the Ceph community also communicates in real -time using `Internet Relay Chat`_. - -.. _`Internet Relay Chat`: http://www.irchelp.org/ - -See https://ceph.com/irc/ for how to set up your IRC -client and a list of channels. - -Submitting patches ------------------- - -The canonical instructions for submitting patches are contained in the -`the file CONTRIBUTING.rst in the top-level directory of the source-code -tree`_. There may be some overlap between this guide and that file. - -.. _`the file CONTRIBUTING.rst in the top-level directory of the source-code tree`: - https://github.com/ceph/ceph/blob/master/CONTRIBUTING.rst - -All newcomers are encouraged to read that file carefully. - -Building from source --------------------- - -See instructions at :doc:`/install/build-ceph`. - -Using ccache to speed up local builds -------------------------------------- - -Rebuilds of the ceph source tree can benefit significantly from use of `ccache`_. -Many a times while switching branches and such, one might see build failures for -certain older branches mostly due to older build artifacts. These rebuilds can -significantly benefit the use of ccache. For a full clean source tree, one could -do :: - - $ make clean - - # note the following will nuke everything in the source tree that - # isn't tracked by git, so make sure to backup any log files /conf options - - $ git clean -fdx; git submodule foreach git clean -fdx - -ccache is available as a package in most distros. To build ceph with ccache one -can:: - - $ cmake -DWITH_CCACHE=ON .. - -ccache can also be used for speeding up all builds in the system. for more -details refer to the `run modes`_ of the ccache manual. The default settings of -``ccache`` can be displayed with ``ccache -s``. - -.. note: It is recommended to override the ``max_size``, which is the size of - cache, defaulting to 10G, to a larger size like 25G or so. Refer to the - `configuration`_ section of ccache manual. - -.. _`ccache`: https://ccache.samba.org/ -.. _`run modes`: https://ccache.samba.org/manual.html#_run_modes -.. _`configuration`: https://ccache.samba.org/manual.html#_configuration - -Development-mode cluster ------------------------- - -See :doc:`/dev/quick_guide`. - -Backporting ------------ - -All bugfixes should be merged to the ``master`` branch before being backported. -To flag a bugfix for backporting, make sure it has a `tracker issue`_ -associated with it and set the ``Backport`` field to a comma-separated list of -previous releases (e.g. "hammer,jewel") that you think need the backport. -The rest (including the actual backporting) will be taken care of by the -`Stable Releases and Backports`_ team. - -.. _`tracker issue`: http://tracker.ceph.com/ -.. _`Stable Releases and Backports`: http://tracker.ceph.com/projects/ceph-releases/wiki - -Guidance for use of cluster log -------------------------------- - -If your patches emit messages to the Ceph cluster log, please consult -this guidance: :doc:`/dev/logging`. - - -What is merged where and when ? -=============================== - -Commits are merged into branches according to criteria that change -during the lifecycle of a Ceph release. This chapter is the inventory -of what can be merged in which branch at a given point in time. - -Development releases (i.e. x.0.z) ---------------------------------- - -What ? -^^^^^^ - -* features -* bug fixes - -Where ? -^^^^^^^ - -Features are merged to the master branch. Bug fixes should be merged -to the corresponding named branch (e.g. "jewel" for 10.0.z, "kraken" -for 11.0.z, etc.). However, this is not mandatory - bug fixes can be -merged to the master branch as well, since the master branch is -periodically merged to the named branch during the development -releases phase. In either case, if the bugfix is important it can also -be flagged for backport to one or more previous stable releases. - -When ? -^^^^^^ - -After the stable release candidates of the previous release enters -phase 2 (see below). For example: the "jewel" named branch was -created when the infernalis release candidates entered phase 2. From -this point on, master was no longer associated with infernalis. As -soon as the named branch of the next stable release is created, master -starts getting periodically merged into it. - -Branch merges -^^^^^^^^^^^^^ - -* The branch of the stable release is merged periodically into master. -* The master branch is merged periodically into the branch of the - stable release. -* The master is merged into the branch of the stable release - immediately after each development x.0.z release. - -Stable release candidates (i.e. x.1.z) phase 1 ----------------------------------------------- - -What ? -^^^^^^ - -* bug fixes only - -Where ? -^^^^^^^ - -The branch of the stable release (e.g. "jewel" for 10.0.z, "kraken" -for 11.0.z, etc.) or master. Bug fixes should be merged to the named -branch corresponding to the stable release candidate (e.g. "jewel" for -10.1.z) or to master. During this phase, all commits to master will be -merged to the named branch, and vice versa. In other words, it makes -no difference whether a commit is merged to the named branch or to -master - it will make it into the next release candidate either way. - -When ? -^^^^^^ - -After the first stable release candidate is published, i.e. after the -x.1.0 tag is set in the release branch. - -Branch merges -^^^^^^^^^^^^^ - -* The branch of the stable release is merged periodically into master. -* The master branch is merged periodically into the branch of the - stable release. -* The master is merged into the branch of the stable release - immediately after each x.1.z release candidate. - -Stable release candidates (i.e. x.1.z) phase 2 ----------------------------------------------- - -What ? -^^^^^^ - -* bug fixes only - -Where ? -^^^^^^^ - -The branch of the stable release (e.g. "jewel" for 10.0.z, "kraken" -for 11.0.z, etc.). During this phase, all commits to the named branch -will be merged into master. Cherry-picking to the named branch during -release candidate phase 2 is done manually since the official -backporting process only begins when the release is pronounced -"stable". - -When ? -^^^^^^ - -After Sage Weil decides it is time for phase 2 to happen. - -Branch merges -^^^^^^^^^^^^^ - -* The branch of the stable release is merged periodically into master. - -Stable releases (i.e. x.2.z) ----------------------------- - -What ? -^^^^^^ - -* bug fixes -* features are sometime accepted -* commits should be cherry-picked from master when possible -* commits that are not cherry-picked from master must be about a bug unique to the stable release -* see also `the backport HOWTO`_ - -.. _`the backport HOWTO`: - http://tracker.ceph.com/projects/ceph-releases/wiki/HOWTO#HOWTO - -Where ? -^^^^^^^ - -The branch of the stable release (hammer for 0.94.x, infernalis for 9.2.x, etc.) - -When ? -^^^^^^ - -After the stable release is published, i.e. after the "vx.2.0" tag is -set in the release branch. - -Branch merges -^^^^^^^^^^^^^ - -Never - -Issue tracker -============= - -See `Redmine issue tracker`_ for a brief introduction to the Ceph Issue Tracker. - -Ceph developers use the issue tracker to - -1. keep track of issues - bugs, fix requests, feature requests, backport -requests, etc. - -2. communicate with other developers and keep them informed as work -on the issues progresses. - -Issue tracker conventions -------------------------- - -When you start working on an existing issue, it's nice to let the other -developers know this - to avoid duplication of labor. Typically, this is -done by changing the :code:`Assignee` field (to yourself) and changing the -:code:`Status` to *In progress*. Newcomers to the Ceph community typically do not -have sufficient privileges to update these fields, however: they can -simply update the issue with a brief note. - -.. table:: Meanings of some commonly used statuses - - ================ =========================================== - Status Meaning - ================ =========================================== - New Initial status - In Progress Somebody is working on it - Need Review Pull request is open with a fix - Pending Backport Fix has been merged, backport(s) pending - Resolved Fix and backports (if any) have been merged - ================ =========================================== - -Basic workflow -============== - -The following chart illustrates basic development workflow: - -.. ditaa:: - - Upstream Code Your Local Environment - - /----------\ git clone /-------------\ - | Ceph | -------------------------> | ceph/master | - \----------/ \-------------/ - ^ | - | | git branch fix_1 - | git merge | - | v - /----------------\ git commit --amend /-------------\ - | make check |---------------------> | ceph/fix_1 | - | ceph--qa--suite| \-------------/ - \----------------/ | - ^ | fix changes - | | test changes - | review | git commit - | | - | v - /--------------\ /-------------\ - | github |<---------------------- | ceph/fix_1 | - | pull request | git push \-------------/ - \--------------/ - -Below we present an explanation of this chart. The explanation is written -with the assumption that you, the reader, are a beginning developer who -has an idea for a bugfix, but do not know exactly how to proceed. - -Update the tracker ------------------- - -Before you start, you should know the `Issue tracker`_ number of the bug -you intend to fix. If there is no tracker issue, now is the time to create -one. - -The tracker is there to explain the issue (bug) to your fellow Ceph -developers and keep them informed as you make progress toward resolution. -To this end, then, provide a descriptive title as well as sufficient -information and details in the description. - -If you have sufficient tracker permissions, assign the bug to yourself by -changing the ``Assignee`` field. If your tracker permissions have not yet -been elevated, simply add a comment to the issue with a short message like -"I am working on this issue". - -Upstream code -------------- - -This section, and the ones that follow, correspond to the nodes in the -above chart. - -The upstream code lives in https://github.com/ceph/ceph.git, which is -sometimes referred to as the "upstream repo", or simply "upstream". As the -chart illustrates, we will make a local copy of this code, modify it, test -our modifications, and submit the modifications back to the upstream repo -for review. - -A local copy of the upstream code is made by - -1. forking the upstream repo on GitHub, and -2. cloning your fork to make a local working copy - -See the `the GitHub documentation -`_ for -detailed instructions on forking. In short, if your GitHub username is -"mygithubaccount", your fork of the upstream repo will show up at -https://github.com/mygithubaccount/ceph. Once you have created your fork, -you clone it by doing: - -.. code:: - - $ git clone https://github.com/mygithubaccount/ceph - -While it is possible to clone the upstream repo directly, in this case you -must fork it first. Forking is what enables us to open a `GitHub pull -request`_. - -For more information on using GitHub, refer to `GitHub Help -`_. - -Local environment ------------------ - -In the local environment created in the previous step, you now have a -copy of the ``master`` branch in ``remotes/origin/master``. Since the fork -(https://github.com/mygithubaccount/ceph.git) is frozen in time and the -upstream repo (https://github.com/ceph/ceph.git, typically abbreviated to -``ceph/ceph.git``) is updated frequently by other developers, you will need -to sync your fork periodically. To do this, first add the upstream repo as -a "remote" and fetch it:: - - $ git remote add ceph https://github.com/ceph/ceph.git - $ git fetch ceph - -Fetching downloads all objects (commits, branches) that were added since -the last sync. After running these commands, all the branches from -``ceph/ceph.git`` are downloaded to the local git repo as -``remotes/ceph/$BRANCH_NAME`` and can be referenced as -``ceph/$BRANCH_NAME`` in certain git commands. - -For example, your local ``master`` branch can be reset to the upstream Ceph -``master`` branch by doing:: - - $ git fetch ceph - $ git checkout master - $ git reset --hard ceph/master - -Finally, the ``master`` branch of your fork can then be synced to upstream -master by:: - - $ git push -u origin master - -Bugfix branch -------------- - -Next, create a branch for the bugfix: - -.. code:: - - $ git checkout master - $ git checkout -b fix_1 - $ git push -u origin fix_1 - -This creates a ``fix_1`` branch locally and in our GitHub fork. At this -point, the ``fix_1`` branch is identical to the ``master`` branch, but not -for long! You are now ready to modify the code. - -Fix bug locally ---------------- - -At this point, change the status of the tracker issue to "In progress" to -communicate to the other Ceph developers that you have begun working on a -fix. If you don't have permission to change that field, your comment that -you are working on the issue is sufficient. - -Possibly, your fix is very simple and requires only minimal testing. -More likely, it will be an iterative process involving trial and error, not -to mention skill. An explanation of how to fix bugs is beyond the -scope of this document. Instead, we focus on the mechanics of the process -in the context of the Ceph project. - -A detailed discussion of the tools available for validating your bugfixes, -see the `Testing`_ chapter. - -For now, let us just assume that you have finished work on the bugfix and -that you have tested it and believe it works. Commit the changes to your local -branch using the ``--signoff`` option:: - - $ git commit -as - -and push the changes to your fork:: - - $ git push origin fix_1 - -GitHub pull request -------------------- - -The next step is to open a GitHub pull request. The purpose of this step is -to make your bugfix available to the community of Ceph developers. They -will review it and may do additional testing on it. - -In short, this is the point where you "go public" with your modifications. -Psychologically, you should be prepared to receive suggestions and -constructive criticism. Don't worry! In our experience, the Ceph project is -a friendly place! - -If you are uncertain how to use pull requests, you may read -`this GitHub pull request tutorial`_. - -.. _`this GitHub pull request tutorial`: - https://help.github.com/articles/using-pull-requests/ - -For some ideas on what constitutes a "good" pull request, see -the `Git Commit Good Practice`_ article at the `OpenStack Project Wiki`_. - -.. _`Git Commit Good Practice`: https://wiki.openstack.org/wiki/GitCommitMessages -.. _`OpenStack Project Wiki`: https://wiki.openstack.org/wiki/Main_Page - -Once your pull request (PR) is opened, update the `Issue tracker`_ by -adding a comment to the bug pointing the other developers to your PR. The -update can be as simple as:: - - *PR*: https://github.com/ceph/ceph/pull/$NUMBER_OF_YOUR_PULL_REQUEST - -Automated PR validation ------------------------ - -When your PR hits GitHub, the Ceph project's `Continuous Integration (CI) -`_ -infrastructure will test it automatically. At the time of this writing -(March 2016), the automated CI testing included a test to check that the -commits in the PR are properly signed (see `Submitting patches`_) and a -`make check`_ test. - -The latter, `make check`_, builds the PR and runs it through a battery of -tests. These tests run on machines operated by the Ceph Continuous -Integration (CI) team. When the tests complete, the result will be shown -on GitHub in the pull request itself. - -You can (and should) also test your modifications before you open a PR. -Refer to the `Testing`_ chapter for details. - -Notes on PR make check test -^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -The GitHub `make check`_ test is driven by a Jenkins instance. - -Jenkins merges the PR branch into the latest version of the base branch before -starting the build, so you don't have to rebase the PR to pick up any fixes. - -You can trigger the PR tests at any time by adding a comment to the PR - the -comment should contain the string "test this please". Since a human subscribed -to the PR might interpret that as a request for him or her to test the PR, it's -good to write the request as "Jenkins, test this please". - -The `make check`_ log is the place to go if there is a failure and you're not -sure what caused it. To reach it, first click on "details" (next to the `make -check`_ test in the PR) to get into the Jenkins web GUI, and then click on -"Console Output" (on the left). - -Jenkins is set up to grep the log for strings known to have been associated -with `make check`_ failures in the past. However, there is no guarantee that -the strings are associated with any given `make check`_ failure. You have to -dig into the log to be sure. - -Integration tests AKA ceph-qa-suite ------------------------------------ - -Since Ceph is a complex beast, it may also be necessary to test your fix to -see how it behaves on real clusters running either on real or virtual -hardware. Tests designed for this purpose live in the `ceph/qa -sub-directory`_ and are run via the `teuthology framework`_. - -.. _`ceph/qa sub-directory`: https://github.com/ceph/ceph/tree/master/qa/ -.. _`teuthology repository`: https://github.com/ceph/teuthology -.. _`teuthology framework`: https://github.com/ceph/teuthology - -If you have access to an OpenStack tenant, you are encouraged to run the -integration tests yourself using `ceph-workbench ceph-qa-suite`_, -and to post the test results to the PR. - -.. _`ceph-workbench ceph-qa-suite`: http://ceph-workbench.readthedocs.org/ - -The Ceph community has access to the `Sepia lab -`_ where integration tests can be run on -real hardware. Other developers may add tags like "needs-qa" to your PR. -This allows PRs that need testing to be merged into a single branch and -tested all at the same time. Since teuthology suites can take hours -(even days in some cases) to run, this can save a lot of time. - -Integration testing is discussed in more detail in the `Testing`_ chapter. - -Code review ------------ - -Once your bugfix has been thoroughly tested, or even during this process, -it will be subjected to code review by other developers. This typically -takes the form of correspondence in the PR itself, but can be supplemented -by discussions on `IRC`_ and the `Mailing list`_. - -Amending your PR ----------------- - -While your PR is going through `Testing`_ and `Code review`_, you can -modify it at any time by editing files in your local branch. - -After the changes are committed locally (to the ``fix_1`` branch in our -example), they need to be pushed to GitHub so they appear in the PR. - -Modifying the PR is done by adding commits to the ``fix_1`` branch upon -which it is based, often followed by rebasing to modify the branch's git -history. See `this tutorial -`_ for a good -introduction to rebasing. When you are done with your modifications, you -will need to force push your branch with: - -.. code:: - - $ git push --force origin fix_1 - -Merge ------ - -The bugfixing process culminates when one of the project leads decides to -merge your PR. - -When this happens, it is a signal for you (or the lead who merged the PR) -to change the `Issue tracker`_ status to "Resolved". Some issues may be -flagged for backporting, in which case the status should be changed to -"Pending Backport" (see the `Backporting`_ chapter for details). - - -Testing -======= - -Ceph has two types of tests: `make check`_ tests and integration tests. -The former are run via `GNU Make `, -and the latter are run via the `teuthology framework`_. The following two -chapters examine the `make check`_ and integration tests in detail. - -.. _`make check`: - -Testing - make check -==================== - -After compiling Ceph, the `make check`_ command can be used to run the -code through a battery of tests covering various aspects of Ceph. For -inclusion in `make check`_, a test must: - -* bind ports that do not conflict with other tests -* not require root access -* not require more than one machine to run -* complete within a few minutes - -While it is possible to run `make check`_ directly, it can be tricky to -correctly set up your environment. Fortunately, a script is provided to -make it easier run `make check`_ on your code. It can be run from the -top-level directory of the Ceph source tree by doing:: - - $ ./run-make-check.sh - -You will need a minimum of 8GB of RAM and 32GB of free disk space for this -command to complete successfully on x86_64 (other architectures may have -different constraints). Depending on your hardware, it can take from 20 -minutes to three hours to complete, but it's worth the wait. - -Caveats -------- - -1. Unlike the various Ceph daemons and ``ceph-fuse``, the `make check`_ tests - are linked against the default memory allocator (glibc) unless explicitly - linked against something else. This enables tools like valgrind to be used - in the tests. - -Testing - integration tests -=========================== - -When a test requires multiple machines, root access or lasts for a -longer time (for example, to simulate a realistic Ceph deployment), it -is deemed to be an integration test. Integration tests are organized into -"suites", which are defined in the `ceph/qa sub-directory`_ and run with -the ``teuthology-suite`` command. - -The ``teuthology-suite`` command is part of the `teuthology framework`_. -In the sections that follow we attempt to provide a detailed introduction -to that framework from the perspective of a beginning Ceph developer. - -Teuthology consumes packages ----------------------------- - -It may take some time to understand the significance of this fact, but it -is `very` significant. It means that automated tests can be conducted on -multiple platforms using the same packages (RPM, DEB) that can be -installed on any machine running those platforms. - -Teuthology has a `list of platforms that it supports -`_ (as -of March 2016 the list consisted of "CentOS 7.2" and "Ubuntu 14.04"). It -expects to be provided pre-built Ceph packages for these platforms. -Teuthology deploys these platforms on machines (bare-metal or -cloud-provisioned), installs the packages on them, and deploys Ceph -clusters on them - all as called for by the test. - -The nightlies -------------- - -A number of integration tests are run on a regular basis in the `Sepia -lab`_ against the official Ceph repositories (on the ``master`` development -branch and the stable branches). Traditionally, these tests are called "the -nightlies" because the Ceph core developers used to live and work in -the same time zone and from their perspective the tests were run overnight. - -The results of the nightlies are published at http://pulpito.ceph.com/ and -http://pulpito.ovh.sepia.ceph.com:8081/. The developer nick shows in the -test results URL and in the first column of the Pulpito dashboard. The -results are also reported on the `ceph-qa mailing list -`_ for analysis. - -Suites inventory ----------------- - -The ``suites`` directory of the `ceph/qa sub-directory`_ contains -all the integration tests, for all the Ceph components. - -`ceph-deploy `_ - install a Ceph cluster with ``ceph-deploy`` (`ceph-deploy man page`_) - -`ceph-disk `_ - verify init scripts (upstart etc.) and udev integration with - ``ceph-disk`` (`ceph-disk man page`_), with and without `dmcrypt - `_ support. - -`dummy `_ - get a machine, do nothing and return success (commonly used to - verify the integration testing infrastructure works as expected) - -`fs `_ - test CephFS - -`kcephfs `_ - test the CephFS kernel module - -`krbd `_ - test the RBD kernel module - -`powercycle `_ - verify the Ceph cluster behaves when machines are powered off - and on again - -`rados `_ - run Ceph clusters including OSDs and MONs, under various conditions of - stress - -`rbd `_ - run RBD tests using actual Ceph clusters, with and without qemu - -`rgw `_ - run RGW tests using actual Ceph clusters - -`smoke `_ - run tests that exercise the Ceph API with an actual Ceph cluster - -`teuthology `_ - verify that teuthology can run integration tests, with and without OpenStack - -`upgrade `_ - for various versions of Ceph, verify that upgrades can happen - without disrupting an ongoing workload - -.. _`ceph-deploy man page`: ../../man/8/ceph-deploy -.. _`ceph-disk man page`: ../../man/8/ceph-disk - -teuthology-describe-tests -------------------------- - -In February 2016, a new feature called ``teuthology-describe-tests`` was -added to the `teuthology framework`_ to facilitate documentation and better -understanding of integration tests (`feature announcement -`_). - -The upshot is that tests can be documented by embedding ``meta:`` -annotations in the yaml files used to define the tests. The results can be -seen in the `ceph-qa-suite wiki -`_. - -Since this is a new feature, many yaml files have yet to be annotated. -Developers are encouraged to improve the documentation, in terms of both -coverage and quality. - -How integration tests are run ------------------------------ - -Given that - as a new Ceph developer - you will typically not have access -to the `Sepia lab`_, you may rightly ask how you can run the integration -tests in your own environment. - -One option is to set up a teuthology cluster on bare metal. Though this is -a non-trivial task, it `is` possible. Here are `some notes -`_ to get you started -if you decide to go this route. - -If you have access to an OpenStack tenant, you have another option: the -`teuthology framework`_ has an OpenStack backend, which is documented `here -`__. -This OpenStack backend can build packages from a given git commit or -branch, provision VMs, install the packages and run integration tests -on those VMs. This process is controlled using a tool called -`ceph-workbench ceph-qa-suite`_. This tool also automates publishing of -test results at http://teuthology-logs.public.ceph.com. - -Running integration tests on your code contributions and publishing the -results allows reviewers to verify that changes to the code base do not -cause regressions, or to analyze test failures when they do occur. - -Every teuthology cluster, whether bare-metal or cloud-provisioned, has a -so-called "teuthology machine" from which tests suites are triggered using the -``teuthology-suite`` command. - -A detailed and up-to-date description of each `teuthology-suite`_ option is -available by running the following command on the teuthology machine:: - - $ teuthology-suite --help - -.. _teuthology-suite: http://docs.ceph.com/teuthology/docs/teuthology.suite.html - -How integration tests are defined ---------------------------------- - -Integration tests are defined by yaml files found in the ``suites`` -subdirectory of the `ceph/qa sub-directory`_ and implemented by python -code found in the ``tasks`` subdirectory. Some tests ("standalone tests") -are defined in a single yaml file, while other tests are defined by a -directory tree containing yaml files that are combined, at runtime, into a -larger yaml file. - -Reading a standalone test -------------------------- - -Let us first examine a standalone test, or "singleton". - -Here is a commented example using the integration test -`rados/singleton/all/admin-socket.yaml -`_ -:: - - roles: - - - mon.a - - osd.0 - - osd.1 - tasks: - - install: - - ceph: - - admin_socket: - osd.0: - version: - git_version: - help: - config show: - config set filestore_dump_file /tmp/foo: - perf dump: - perf schema: - -The ``roles`` array determines the composition of the cluster (how -many MONs, OSDs, etc.) on which this test is designed to run, as well -as how these roles will be distributed over the machines in the -testing cluster. In this case, there is only one element in the -top-level array: therefore, only one machine is allocated to the -test. The nested array declares that this machine shall run a MON with -id ``a`` (that is the ``mon.a`` in the list of roles) and two OSDs -(``osd.0`` and ``osd.1``). - -The body of the test is in the ``tasks`` array: each element is -evaluated in order, causing the corresponding python file found in the -``tasks`` subdirectory of the `teuthology repository`_ or -`ceph/qa sub-directory`_ to be run. "Running" in this case means calling -the ``task()`` function defined in that file. - -In this case, the `install -`_ -task comes first. It installs the Ceph packages on each machine (as -defined by the ``roles`` array). A full description of the ``install`` -task is `found in the python file -`_ -(search for "def task"). - -The ``ceph`` task, which is documented `here -`__ (again, -search for "def task"), starts OSDs and MONs (and possibly MDSs as well) -as required by the ``roles`` array. In this example, it will start one MON -(``mon.a``) and two OSDs (``osd.0`` and ``osd.1``), all on the same -machine. Control moves to the next task when the Ceph cluster reaches -``HEALTH_OK`` state. - -The next task is ``admin_socket`` (`source code -`_). -The parameter of the ``admin_socket`` task (and any other task) is a -structure which is interpreted as documented in the task. In this example -the parameter is a set of commands to be sent to the admin socket of -``osd.0``. The task verifies that each of them returns on success (i.e. -exit code zero). - -This test can be run with:: - - $ teuthology-suite --suite rados/singleton/all/admin-socket.yaml fs/ext4.yaml - -Test descriptions ------------------ - -Each test has a "test description", which is similar to a directory path, -but not the same. In the case of a standalone test, like the one in -`Reading a standalone test`_, the test description is identical to the -relative path (starting from the ``suites/`` directory of the -`ceph/qa sub-directory`_) of the yaml file defining the test. - -Much more commonly, tests are defined not by a single yaml file, but by a -`directory tree of yaml files`. At runtime, the tree is walked and all yaml -files (facets) are combined into larger yaml "programs" that define the -tests. A full listing of the yaml defining the test is included at the -beginning of every test log. - -In these cases, the description of each test consists of the -subdirectory under `suites/ -`_ containing the -yaml facets, followed by an expression in curly braces (``{}``) consisting of -a list of yaml facets in order of concatenation. For instance the -test description:: - - ceph-disk/basic/{distros/centos_7.0.yaml tasks/ceph-disk.yaml} - -signifies the concatenation of two files: - -* ceph-disk/basic/distros/centos_7.0.yaml -* ceph-disk/basic/tasks/ceph-disk.yaml - -How are tests built from directories? -------------------------------------- - -As noted in the previous section, most tests are not defined in a single -yaml file, but rather as a `combination` of files collected from a -directory tree within the ``suites/`` subdirectory of the `ceph/qa sub-directory`_. - -The set of all tests defined by a given subdirectory of ``suites/`` is -called an "integration test suite", or a "teuthology suite". - -Combination of yaml facets is controlled by special files (``%`` and -``+``) that are placed within the directory tree and can be thought of as -operators. The ``%`` file is the "convolution" operator and ``+`` -signifies concatenation. - -Convolution operator --------------------- - -The convolution operator, implemented as an empty file called ``%``, tells -teuthology to construct a test matrix from yaml facets found in -subdirectories below the directory containing the operator. - -For example, the `ceph-disk suite -`_ is -defined by the ``suites/ceph-disk/`` tree, which consists of the files and -subdirectories in the following structure:: - - directory: ceph-disk/basic - file: % - directory: distros - file: centos_7.0.yaml - file: ubuntu_14.04.yaml - directory: tasks - file: ceph-disk.yaml - -This is interpreted as a 2x1 matrix consisting of two tests: - -1. ceph-disk/basic/{distros/centos_7.0.yaml tasks/ceph-disk.yaml} -2. ceph-disk/basic/{distros/ubuntu_14.04.yaml tasks/ceph-disk.yaml} - -i.e. the concatenation of centos_7.0.yaml and ceph-disk.yaml and -the concatenation of ubuntu_14.04.yaml and ceph-disk.yaml, respectively. -In human terms, this means that the task found in ``ceph-disk.yaml`` is -intended to run on both CentOS 7.0 and Ubuntu 14.04. - -Without the file percent, the ``ceph-disk`` tree would be interpreted as -three standalone tests: - -* ceph-disk/basic/distros/centos_7.0.yaml -* ceph-disk/basic/distros/ubuntu_14.04.yaml -* ceph-disk/basic/tasks/ceph-disk.yaml - -(which would of course be wrong in this case). - -Referring to the `ceph/qa sub-directory`_, you will notice that the -``centos_7.0.yaml`` and ``ubuntu_14.04.yaml`` files in the -``suites/ceph-disk/basic/distros/`` directory are implemented as symlinks. -By using symlinks instead of copying, a single file can appear in multiple -suites. This eases the maintenance of the test framework as a whole. - -All the tests generated from the ``suites/ceph-disk/`` directory tree -(also known as the "ceph-disk suite") can be run with:: - - $ teuthology-suite --suite ceph-disk - -An individual test from the `ceph-disk suite`_ can be run by adding the -``--filter`` option:: - - $ teuthology-suite \ - --suite ceph-disk/basic \ - --filter 'ceph-disk/basic/{distros/ubuntu_14.04.yaml tasks/ceph-disk.yaml}' - -.. note: To run a standalone test like the one in `Reading a standalone - test`_, ``--suite`` alone is sufficient. If you want to run a single - test from a suite that is defined as a directory tree, ``--suite`` must - be combined with ``--filter``. This is because the ``--suite`` option - understands POSIX relative paths only. - -Concatenation operator ----------------------- - -For even greater flexibility in sharing yaml files between suites, the -special file plus (``+``) can be used to concatenate files within a -directory. For instance, consider the `suites/rbd/thrash -`_ -tree:: - - directory: rbd/thrash - file: % - directory: clusters - file: + - file: fixed-2.yaml - file: openstack.yaml - directory: workloads - file: rbd_api_tests_copy_on_read.yaml - file: rbd_api_tests.yaml - -This creates two tests: - -* rbd/thrash/{clusters/fixed-2.yaml clusters/openstack.yaml workloads/rbd_api_tests_copy_on_read.yaml} -* rbd/thrash/{clusters/fixed-2.yaml clusters/openstack.yaml workloads/rbd_api_tests.yaml} - -Because the ``clusters/`` subdirectory contains the special file plus -(``+``), all the other files in that subdirectory (``fixed-2.yaml`` and -``openstack.yaml`` in this case) are concatenated together -and treated as a single file. Without the special file plus, they would -have been convolved with the files from the workloads directory to create -a 2x2 matrix: - -* rbd/thrash/{clusters/openstack.yaml workloads/rbd_api_tests_copy_on_read.yaml} -* rbd/thrash/{clusters/openstack.yaml workloads/rbd_api_tests.yaml} -* rbd/thrash/{clusters/fixed-2.yaml workloads/rbd_api_tests_copy_on_read.yaml} -* rbd/thrash/{clusters/fixed-2.yaml workloads/rbd_api_tests.yaml} - -The ``clusters/fixed-2.yaml`` file is shared among many suites to -define the following ``roles``:: - - roles: - - [mon.a, mon.c, osd.0, osd.1, osd.2, client.0] - - [mon.b, osd.3, osd.4, osd.5, client.1] - -The ``rbd/thrash`` suite as defined above, consisting of two tests, -can be run with:: - - $ teuthology-suite --suite rbd/thrash - -A single test from the rbd/thrash suite can be run by adding the -``--filter`` option:: - - $ teuthology-suite \ - --suite rbd/thrash \ - --filter 'rbd/thrash/{clusters/fixed-2.yaml clusters/openstack.yaml workloads/rbd_api_tests_copy_on_read.yaml}' - -Filtering tests by their description ------------------------------------- - -When a few jobs fail and need to be run again, the ``--filter`` option -can be used to select tests with a matching description. For instance, if the -``rados`` suite fails the `all/peer.yaml `_ test, the following will only run the tests that contain this file:: - - teuthology-suite --suite rados --filter all/peer.yaml - -The ``--filter-out`` option does the opposite (it matches tests that do -`not` contain a given string), and can be combined with the ``--filter`` -option. - -Both ``--filter`` and ``--filter-out`` take a comma-separated list of strings (which -means the comma character is implicitly forbidden in filenames found in the -`ceph/qa sub-directory`_). For instance:: - - teuthology-suite --suite rados --filter all/peer.yaml,all/rest-api.yaml - -will run tests that contain either -`all/peer.yaml `_ -or -`all/rest-api.yaml `_ - -Each string is looked up anywhere in the test description and has to -be an exact match: they are not regular expressions. - -Reducing the number of tests ----------------------------- - -The ``rados`` suite generates thousands of tests out of a few hundred -files. This happens because teuthology constructs test matrices from -subdirectories wherever it encounters a file named ``%``. For instance, -all tests in the `rados/basic suite -`_ -run with different messenger types: ``simple``, ``async`` and -``random``, because they are combined (via the special file ``%``) with -the `msgr directory -`_ - -All integration tests are required to be run before a Ceph release is published. -When merely verifying whether a contribution can be merged without -risking a trivial regression, it is enough to run a subset. The ``--subset`` option can be used to -reduce the number of tests that are triggered. For instance:: - - teuthology-suite --suite rados --subset 0/4000 - -will run as few tests as possible. The tradeoff in this case is that -not all combinations of test variations will together, -but no matter how small a ratio is provided in the ``--subset``, -teuthology will still ensure that all files in the suite are in at -least one test. Understanding the actual logic that drives this -requires reading the teuthology source code. - -The ``--limit`` option only runs the first ``N`` tests in the suite: -this is rarely useful, however, because there is no way to control which -test will be first. - -Testing in the cloud -==================== - -In this chapter, we will explain in detail how use an OpenStack -tenant as an environment for Ceph integration testing. - -Assumptions and caveat ----------------------- - -We assume that: - -1. you are the only person using the tenant -2. you have the credentials -3. the tenant supports the ``nova`` and ``cinder`` APIs - -Caveat: be aware that, as of this writing (July 2016), testing in -OpenStack clouds is a new feature. Things may not work as advertised. -If you run into trouble, ask for help on `IRC`_ or the `Mailing list`_, or -open a bug report at the `ceph-workbench bug tracker`_. - -.. _`ceph-workbench bug tracker`: http://ceph-workbench.dachary.org/root/ceph-workbench/issues - -Prepare tenant --------------- - -If you have not tried to use ``ceph-workbench`` with this tenant before, -proceed to the next step. - -To start with a clean slate, login to your tenant via the Horizon dashboard and: - -* terminate the ``teuthology`` and ``packages-repository`` instances, if any -* delete the ``teuthology`` and ``teuthology-worker`` security groups, if any -* delete the ``teuthology`` and ``teuthology-myself`` key pairs, if any - -Also do the above if you ever get key-related errors ("invalid key", etc.) when -trying to schedule suites. - -Getting ceph-workbench ----------------------- - -Since testing in the cloud is done using the `ceph-workbench -ceph-qa-suite`_ tool, you will need to install that first. It is designed -to be installed via Docker, so if you don't have Docker running on your -development machine, take care of that first. You can follow `the official -tutorial `_ to install if -you have not installed yet. - -Once Docker is up and running, install ``ceph-workbench`` by following the -`Installation instructions in the ceph-workbench documentation -`_. - -Linking ceph-workbench with your OpenStack tenant -------------------------------------------------- - -Before you can trigger your first teuthology suite, you will need to link -``ceph-workbench`` with your OpenStack account. - -First, download a ``openrc.sh`` file by clicking on the "Download OpenStack -RC File" button, which can be found in the "API Access" tab of the "Access -& Security" dialog of the OpenStack Horizon dashboard. - -Second, create a ``~/.ceph-workbench`` directory, set its permissions to -700, and move the ``openrc.sh`` file into it. Make sure that the filename -is exactly ``~/.ceph-workbench/openrc.sh``. - -Third, edit the file so it does not ask for your OpenStack password -interactively. Comment out the relevant lines and replace them with -something like:: - - export OS_PASSWORD="aiVeth0aejee3eep8rogho3eep7Pha6ek" - -When `ceph-workbench ceph-qa-suite`_ connects to your OpenStack tenant for -the first time, it will generate two keypairs: ``teuthology-myself`` and -``teuthology``. - -.. If this is not the first time you have tried to use -.. `ceph-workbench ceph-qa-suite`_ with this tenant, make sure to delete any -.. stale keypairs with these names! - -Run the dummy suite -------------------- - -You are now ready to take your OpenStack teuthology setup for a test -drive:: - - $ ceph-workbench ceph-qa-suite --suite dummy - -Be forewarned that the first run of `ceph-workbench ceph-qa-suite`_ on a -pristine tenant will take a long time to complete because it downloads a VM -image and during this time the command may not produce any output. - -The images are cached in OpenStack, so they are only downloaded once. -Subsequent runs of the same command will complete faster. - -Although ``dummy`` suite does not run any tests, in all other respects it -behaves just like a teuthology suite and produces some of the same -artifacts. - -The last bit of output should look something like this:: - - pulpito web interface: http://149.202.168.201:8081/ - ssh access : ssh -i /home/smithfarm/.ceph-workbench/teuthology-myself.pem ubuntu@149.202.168.201 # logs in /usr/share/nginx/html - -What this means is that `ceph-workbench ceph-qa-suite`_ triggered the test -suite run. It does not mean that the suite run has completed. To monitor -progress of the run, check the Pulpito web interface URL periodically, or -if you are impatient, ssh to the teuthology machine using the ssh command -shown and do:: - - $ tail -f /var/log/teuthology.* - -The `/usr/share/nginx/html` directory contains the complete logs of the -test suite. If we had provided the ``--upload`` option to the -`ceph-workbench ceph-qa-suite`_ command, these logs would have been -uploaded to http://teuthology-logs.public.ceph.com. - -Run a standalone test ---------------------- - -The standalone test explained in `Reading a standalone test`_ can be run -with the following command:: - - $ ceph-workbench ceph-qa-suite --suite rados/singleton/all/admin-socket.yaml - -This will run the suite shown on the current ``master`` branch of -``ceph/ceph.git``. You can specify a different branch with the ``--ceph`` -option, and even a different git repo with the ``--ceph-git-url`` option. (Run -``ceph-workbench ceph-qa-suite --help`` for an up-to-date list of available -options.) - -The first run of a suite will also take a long time, because ceph packages -have to be built, first. Again, the packages so built are cached and -`ceph-workbench ceph-qa-suite`_ will not build identical packages a second -time. - -Interrupt a running suite -------------------------- - -Teuthology suites take time to run. From time to time one may wish to -interrupt a running suite. One obvious way to do this is:: - - ceph-workbench ceph-qa-suite --teardown - -This destroys all VMs created by `ceph-workbench ceph-qa-suite`_ and -returns the OpenStack tenant to a "clean slate". - -Sometimes you may wish to interrupt the running suite, but keep the logs, -the teuthology VM, the packages-repository VM, etc. To do this, you can -``ssh`` to the teuthology VM (using the ``ssh access`` command reported -when you triggered the suite -- see `Run the dummy suite`_) and, once -there:: - - sudo /etc/init.d/teuthology restart - -This will keep the teuthology machine, the logs and the packages-repository -instance but nuke everything else. - -Upload logs to archive server ------------------------------ - -Since the teuthology instance in OpenStack is only semi-permanent, with limited -space for storing logs, ``teuthology-openstack`` provides an ``--upload`` -option which, if included in the ``ceph-workbench ceph-qa-suite`` command, -will cause logs from all failed jobs to be uploaded to the log archive server -maintained by the Ceph project. The logs will appear at the URL:: - - http://teuthology-logs.public.ceph.com/$RUN - -where ``$RUN`` is the name of the run. It will be a string like this:: - - ubuntu-2016-07-23_16:08:12-rados-hammer-backports---basic-openstack - -Even if you don't providing the ``--upload`` option, however, all the logs can -still be found on the teuthology machine in the directory -``/usr/share/nginx/html``. - -Provision VMs ad hoc --------------------- - -From the teuthology VM, it is possible to provision machines on an "ad hoc" -basis, to use however you like. The magic incantation is:: - - teuthology-lock --lock-many $NUMBER_OF_MACHINES \ - --os-type $OPERATING_SYSTEM \ - --os-version $OS_VERSION \ - --machine-type openstack \ - --owner $EMAIL_ADDRESS - -The command must be issued from the ``~/teuthology`` directory. The possible -values for ``OPERATING_SYSTEM`` AND ``OS_VERSION`` can be found by examining -the contents of the directory ``teuthology/openstack/``. For example:: - - teuthology-lock --lock-many 1 --os-type ubuntu --os-version 16.04 \ - --machine-type openstack --owner foo@example.com - -When you are finished with the machine, find it in the list of machines:: - - openstack server list - -to determine the name or ID, and then terminate it with:: - - openstack server delete $NAME_OR_ID - -Deploy a cluster for manual testing ------------------------------------ - -The `teuthology framework`_ and `ceph-workbench ceph-qa-suite`_ are -versatile tools that automatically provision Ceph clusters in the cloud and -run various tests on them in an automated fashion. This enables a single -engineer, in a matter of hours, to perform thousands of tests that would -keep dozens of human testers occupied for days or weeks if conducted -manually. - -However, there are times when the automated tests do not cover a particular -scenario and manual testing is desired. It turns out that it is simple to -adapt a test to stop and wait after the Ceph installation phase, and the -engineer can then ssh into the running cluster. Simply add the following -snippet in the desired place within the test YAML and schedule a run with the -test:: - - tasks: - - exec: - client.0: - - sleep 1000000000 # forever - -(Make sure you have a ``client.0`` defined in your ``roles`` stanza or adapt -accordingly.) - -The same effect can be achieved using the ``interactive`` task:: - - tasks: - - interactive - -By following the test log, you can determine when the test cluster has entered -the "sleep forever" condition. At that point, you can ssh to the teuthology -machine and from there to one of the target VMs (OpenStack) or teuthology -worker machines machine (Sepia) where the test cluster is running. - -The VMs (or "instances" in OpenStack terminology) created by -`ceph-workbench ceph-qa-suite`_ are named as follows: - -``teuthology`` - the teuthology machine - -``packages-repository`` - VM where packages are stored - -``ceph-*`` - VM where packages are built - -``target*`` - machines where tests are run - -The VMs named ``target*`` are used by tests. If you are monitoring the -teuthology log for a given test, the hostnames of these target machines can -be found out by searching for the string ``Locked targets``:: - - 2016-03-20T11:39:06.166 INFO:teuthology.task.internal:Locked targets: - target149202171058.teuthology: null - target149202171059.teuthology: null - -The IP addresses of the target machines can be found by running ``openstack -server list`` on the teuthology machine, but the target VM hostnames (e.g. -``target149202171058.teuthology``) are resolvable within the teuthology -cluster. - - -Testing - how to run s3-tests locally -===================================== - -RGW code can be tested by building Ceph locally from source, starting a vstart -cluster, and running the "s3-tests" suite against it. - -The following instructions should work on jewel and above. - -Step 1 - build Ceph -------------------- - -Refer to :doc:`/install/build-ceph`. - -You can do step 2 separately while it is building. - -Step 2 - vstart ---------------- - -When the build completes, and still in the top-level directory of the git -clone where you built Ceph, do the following, for cmake builds:: - - cd build/ - RGW=1 ../vstart.sh -n - -This will produce a lot of output as the vstart cluster is started up. At the -end you should see a message like:: - - started. stop.sh to stop. see out/* (e.g. 'tail -f out/????') for debug output. - -This means the cluster is running. - - -Step 3 - run s3-tests ---------------------- - -To run the s3tests suite do the following:: - - $ ../qa/workunits/rgw/run-s3tests.sh - -.. WIP -.. === -.. -.. Building RPM packages -.. --------------------- -.. -.. Ceph is regularly built and packaged for a number of major Linux -.. distributions. At the time of this writing, these included CentOS, Debian, -.. Fedora, openSUSE, and Ubuntu. -.. -.. Architecture -.. ============ -.. -.. Ceph is a collection of components built on top of RADOS and provide -.. services (RBD, RGW, CephFS) and APIs (S3, Swift, POSIX) for the user to -.. store and retrieve data. -.. -.. See :doc:`/architecture` for an overview of Ceph architecture. The -.. following sections treat each of the major architectural components -.. in more detail, with links to code and tests. -.. -.. FIXME The following are just stubs. These need to be developed into -.. detailed descriptions of the various high-level components (RADOS, RGW, -.. etc.) with breakdowns of their respective subcomponents. -.. -.. FIXME Later, in the Testing chapter I would like to take another look -.. at these components/subcomponents with a focus on how they are tested. -.. -.. RADOS -.. ----- -.. -.. RADOS stands for "Reliable, Autonomic Distributed Object Store". In a Ceph -.. cluster, all data are stored in objects, and RADOS is the component responsible -.. for that. -.. -.. RADOS itself can be further broken down into Monitors, Object Storage Daemons -.. (OSDs), and client APIs (librados). Monitors and OSDs are introduced at -.. :doc:`/start/intro`. The client library is explained at -.. :doc:`/rados/api/index`. -.. -.. RGW -.. --- -.. -.. RGW stands for RADOS Gateway. Using the embedded HTTP server civetweb_ or -.. Apache FastCGI, RGW provides a REST interface to RADOS objects. -.. -.. .. _civetweb: https://github.com/civetweb/civetweb -.. -.. A more thorough introduction to RGW can be found at :doc:`/radosgw/index`. -.. -.. RBD -.. --- -.. -.. RBD stands for RADOS Block Device. It enables a Ceph cluster to store disk -.. images, and includes in-kernel code enabling RBD images to be mounted. -.. -.. To delve further into RBD, see :doc:`/rbd/rbd`. -.. -.. CephFS -.. ------ -.. -.. CephFS is a distributed file system that enables a Ceph cluster to be used as a NAS. -.. -.. File system metadata is managed by Meta Data Server (MDS) daemons. The Ceph -.. file system is explained in more detail at :doc:`/cephfs/index`. -.. -- cgit 1.2.3-korg