ceph

Ceph is a distributed object, block, and file storage platform

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Storage Orchestration for Kubernetes

Quick Overview

Ceph is a distributed storage system designed to provide excellent performance, reliability, and scalability. It offers object, block, and file storage in a unified system, making it suitable for a wide range of use cases, from cloud infrastructure to high-performance computing.

Pros

Highly scalable and flexible, capable of handling exabytes of data
Self-healing and self-managing, reducing operational overhead
Supports multiple storage types (object, block, file) in a single system
Open-source with a strong community and commercial support options

Cons

Complex to set up and manage, especially for smaller deployments
Can be resource-intensive, requiring significant hardware resources
Learning curve for administrators unfamiliar with distributed storage systems
Performance can be inconsistent in certain scenarios, especially with mixed workloads

Getting Started

To get started with Ceph, follow these steps:

Install Ceph on your nodes:

sudo apt update
sudo apt install -y ceph

Create a Ceph configuration file (/etc/ceph/ceph.conf):

[global]
mon_initial_members = node1, node2, node3
mon_host = 10.0.0.1, 10.0.0.2, 10.0.0.3
auth_cluster_required = cephx
auth_service_required = cephx
auth_client_required = cephx

Initialize the Ceph cluster:

ceph-deploy new node1 node2 node3
ceph-deploy mon create-initial
ceph-deploy admin node1 node2 node3
ceph-deploy mgr create node1

Add OSDs (Object Storage Daemons):

ceph-deploy osd create --data /dev/sdb node1
ceph-deploy osd create --data /dev/sdb node2
ceph-deploy osd create --data /dev/sdb node3

Check cluster status:

ceph -s

Note: This is a simplified setup. For production environments, consult the official documentation for best practices and advanced configurations.

Competitor Comparisons

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Gluster Filesystem : Build your distributed storage in minutes

Pros of GlusterFS

Simpler architecture and easier to set up for small to medium-scale deployments
Better performance for large file workloads and sequential read/write operations
Native support for POSIX-compliant file systems

Cons of GlusterFS

Limited scalability compared to Ceph, especially for large-scale deployments
Less flexible in terms of storage backend options and data protection schemes
Lacks built-in object storage capabilities

Code Comparison

GlusterFS volume creation:

gluster volume create myvol replica 2 server1:/exp1 server2:/exp2
gluster volume start myvol

Ceph pool and filesystem creation:

ceph osd pool create mypool 128
ceph fs new myfs mypool mdpool

Both systems use different approaches for creating storage volumes. GlusterFS focuses on a more straightforward volume creation process, while Ceph offers more granular control over pools and filesystems.

GlusterFS is generally easier to set up and manage for smaller deployments, while Ceph provides greater scalability and flexibility for larger, more complex environments. The choice between the two depends on specific use cases, scalability requirements, and desired features.

minio

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MinIO is a high-performance, S3 compatible object store, open sourced under GNU AGPLv3 license.

Pros of MinIO

Simpler to set up and manage, especially for smaller deployments
Designed specifically for object storage, with S3 compatibility as a primary focus
Lightweight and can run on a single node, making it suitable for edge computing

Cons of MinIO

Less scalable for extremely large deployments compared to Ceph's distributed architecture
Fewer advanced features and storage types (e.g., block and file storage) than Ceph
Limited support for erasure coding configurations

Code Comparison

MinIO (Go):

func (xl xlObjects) PutObject(ctx context.Context, bucket, object string, data *PutObjReader, opts ObjectOptions) (objInfo ObjectInfo, err error) {
    // Implementation for putting an object
}

Ceph (C++):

int librados::IoCtx::write(const std::string& oid, bufferlist& bl, size_t len, uint64_t off)
{
    // Implementation for writing data to an object
}

Both projects use different languages and approaches, with MinIO focusing on S3-compatible object storage in Go, while Ceph provides a more comprehensive storage solution in C++.

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Pros of SeaweedFS

Simpler architecture and easier to set up and maintain
Better performance for small file storage and retrieval
Lower resource requirements, making it more suitable for smaller deployments

Cons of SeaweedFS

Less mature and battle-tested compared to Ceph's extensive production use
Limited support for advanced features like erasure coding and tiered storage
Smaller community and ecosystem, potentially leading to fewer integrations and third-party tools

Code Comparison

SeaweedFS (Go):

func (vs *VolumeServer) autoVacuum() {
    for {
        if vs.isStopping {
            return
        }
        vs.vacuum()
        time.Sleep(time.Duration(vs.vacuumPeriodMinutes) * time.Minute)
    }
}

Ceph (C++):

int BlueStore::_do_write(
  TransContext *txc,
  CollectionRef& c,
  OnodeRef& o,
  uint64_t offset,
  uint64_t length,
  bufferlist& bl,
  uint32_t fadvise_flags)
{
  // implementation details
}

Both projects implement distributed storage systems, but SeaweedFS focuses on simplicity and efficiency for small files, while Ceph offers a more comprehensive and feature-rich solution for large-scale deployments. The code snippets showcase the different languages used (Go vs. C++) and highlight the varying complexity levels in their implementations.

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Pros of Storj

Decentralized architecture, offering improved data privacy and resilience
Incentivized network of node operators, potentially reducing storage costs
Designed for easy integration with existing cloud storage systems

Cons of Storj

Relatively newer project with a smaller community compared to Ceph
May have higher latency due to distributed nature of the network
Limited support for advanced enterprise features found in Ceph

Code Comparison

Storj (Go):

func (db *DB) Get(ctx context.Context, bucket, key string) (_ []byte, err error) {
    defer mon.Task()(&ctx)(&err)
    return db.client.GetObject(ctx, bucket, key, minio.GetObjectOptions{})
}

Ceph (C++):

int librados::IoCtx::read(const std::string& oid, bufferlist& bl, size_t len, uint64_t off)
{
  return client->read(this, oid, bl, len, off);
}

The Storj code snippet shows a method for retrieving an object from storage, while the Ceph example demonstrates a read operation on a specific object. Storj uses Go and integrates with S3-compatible APIs, whereas Ceph is written in C++ and provides a lower-level interface for object storage operations.

rook

12,759

Storage Orchestration for Kubernetes

Pros of Rook

Simplified deployment and management of Ceph clusters in Kubernetes environments
Broader support for multiple storage providers beyond Ceph
Tighter integration with Kubernetes native concepts and resources

Cons of Rook

Less mature and battle-tested compared to the standalone Ceph project
Limited to Kubernetes environments, lacking support for traditional deployments
Potentially less flexibility in advanced Ceph configurations

Code Comparison

Rook (Kubernetes-native approach):

apiVersion: ceph.rook.io/v1
kind: CephCluster
metadata:
  name: rook-ceph
  namespace: rook-ceph
spec:
  cephVersion:
    image: ceph/ceph:v15.2.8

Ceph (Traditional deployment):

ceph-deploy new node1 node2 node3
ceph-deploy install node1 node2 node3
ceph-deploy mon create-initial
ceph-deploy admin node1 node2 node3
ceph-deploy mgr create node1

The code snippets highlight the difference in deployment approaches. Rook uses Kubernetes custom resources, while Ceph relies on command-line tools for traditional deployments.

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README

Ceph - a scalable distributed storage system

See https://ceph.com/ for current information about Ceph.

Status

Contributing Code

Most of Ceph is dual-licensed under the LGPL version 2.1 or 3.0. Some miscellaneous code is either public domain or licensed under a BSD-style license.

The Ceph documentation is licensed under Creative Commons Attribution Share Alike 3.0 (CC-BY-SA-3.0).

Some headers included in the ceph/ceph repository are licensed under the GPL. See the file COPYING for a full inventory of licenses by file.

All code contributions must include a valid "Signed-off-by" line. See the file SubmittingPatches.rst for details on this and instructions on how to generate and submit patches.

Assignment of copyright is not required to contribute code. Code is contributed under the terms of the applicable license.

Checking out the source

Clone the ceph/ceph repository from github by running the following command on a system that has git installed:

git clone git@github.com:ceph/ceph

Alternatively, if you are not a github user, you should run the following command on a system that has git installed:

git clone https://github.com/ceph/ceph.git

When the ceph/ceph repository has been cloned to your system, run the following commands to move into the cloned ceph/ceph repository and to check out the git submodules associated with it:

cd ceph
git submodule update --init --recursive --progress

Build Prerequisites

section last updated 06 Sep 2024

We provide the Debian and Ubuntu apt commands in this procedure. If you use a system with a different package manager, then you will have to use different commands.

#. Install curl:

apt install curl

#. Install package dependencies by running the install-deps.sh script:

./install-deps.sh

#. Install the python3-routes package:

apt install python3-routes

Building Ceph

These instructions are meant for developers who are compiling the code for development and testing. To build binaries that are suitable for installation we recommend that you build .deb or .rpm packages, or refer to ceph.spec.in or debian/rules to see which configuration options are specified for production builds.

To build Ceph, follow this procedure:

Make sure that you are in the top-level ceph directory that contains do_cmake.sh and CONTRIBUTING.rst.
Run the do_cmake.sh script:
```
./do_cmake.sh
```
do_cmake.sh by default creates a "debug build" of Ceph, which can be up to five times slower than a non-debug build. Pass -DCMAKE_BUILD_TYPE=RelWithDebInfo to do_cmake.sh to create a non-debug build.
Move into the build directory:
```
cd build
```
Use the ninja buildsystem to build the development environment:
```
ninja -j3
```
[!IMPORTANT]

Ninja is the build system used by the Ceph project to build test builds. The number of jobs used by ninja is derived from the number of CPU cores of the building host if unspecified. Use the -j option to limit the job number if build jobs are running out of memory. If you attempt to run ninja and receive a message that reads g++: fatal error: Killed signal terminated program cc1plus, then you have run out of memory.

Using the -j option with an argument appropriate to the hardware on which the ninja command is run is expected to result in a successful build. For example, to limit the job number to 3, run the command ninja -j3. On average, each ninja job run in parallel needs approximately 2.5 GiB of RAM.

This documentation assumes that your build directory is a subdirectory of the ceph.git checkout. If the build directory is located elsewhere, point CEPH_GIT_DIR to the correct path of the checkout. Additional CMake args can be specified by setting ARGS before invoking do_cmake.sh. See cmake options for more details. For example:
```
ARGS="-DCMAKE_C_COMPILER=gcc-7" ./do_cmake.sh
```
To build only certain targets, run a command of the following form:
```
ninja [target name]
```
Install the vstart cluster:
```
ninja install
```

CMake Options

The -D flag can be used with cmake to speed up the process of building Ceph and to customize the build.

Building without RADOS Gateway

The RADOS Gateway is built by default. To build Ceph without the RADOS Gateway, run a command of the following form:

cmake -DWITH_RADOSGW=OFF [path to top-level ceph directory]

Building with debugging and arbitrary dependency locations

Run a command of the following form to build Ceph with debugging and alternate locations for some external dependencies:

cmake -DCMAKE_INSTALL_PREFIX=/opt/ceph -DCMAKE_C_FLAGS="-Og -g3 -gdwarf-4" \
..

Ceph has several bundled dependencies such as Boost, RocksDB and Arrow. By default, cmake builds these bundled dependencies from source instead of using libraries that are already installed on the system. You can opt to use these system libraries, as long as they meet Ceph's version requirements. To use system libraries, use cmake options like WITH_SYSTEM_BOOST, as in the following example:

cmake -DWITH_SYSTEM_BOOST=ON [...]

To view an exhaustive list of -D options, invoke cmake -LH:

cmake -LH

Preserving diagnostic colors

If you pipe ninja to less and would like to preserve the diagnostic colors in the output in order to make errors and warnings more legible, run the following command:

cmake -DDIAGNOSTICS_COLOR=always ...

The above command works only with supported compilers.

The diagnostic colors will be visible when the following command is run:

ninja | less -R

Other available values for DIAGNOSTICS_COLOR are auto (default) and never.

Tips and Tricks

Use "debug builds" only when needed. Debugging builds are helpful for development, but they can slow down performance. Use -DCMAKE_BUILD_TYPE=Release when debugging isn't necessary.
Enable Selective Daemons when testing specific components. Don't start unnecessary daemons.
Preserve Existing Data skip cluster reinitialization between tests by using the -n flag.
To manage a vstart cluster, stop daemons using ./stop.sh and start them with ./vstart.sh --daemon osd.${ID} [--nodaemonize].
Restart the sockets by stopping and restarting the daemons associated with them. This ensures that there are no stale sockets in the cluster.
To track RocksDB performance, set export ROCKSDB_PERF=true and start the cluster by using the command ./vstart.sh -n -d -x --bluestore.
Build with vstart-base using debug flags in cmake, compile, and deploy via ./vstart.sh -d -n --bluestore.
To containerize, generate configurations with vstart.sh, and deploy with Docker, mapping directories and configuring the network.
Manage containers using docker run, stop, and rm. For detailed setups, consult the Ceph-Container repository.

Troubleshooting

Cluster Fails to Start: Look for errors in the logs under the out/ directory.
OSD Crashes: Check the OSD logs for errors.
Cluster in a Health Error State: Run the ceph status command to identify the issue.
RocksDB Errors: Look for RocksDB-related errors in the OSD logs.

Building a source tarball

To build a complete source tarball with everything needed to build from source and/or build a (deb or rpm) package, run

./make-dist

This will create a tarball like ceph-$version.tar.bz2 from git. (Ensure that any changes you want to include in your working directory are committed to git.)

Running a test cluster

From the ceph/ directory, run the following commands to launch a test Ceph cluster:

cd build
ninja vstart        # builds just enough to run vstart
../src/vstart.sh --debug --new -x --localhost --bluestore
./bin/ceph -s

Most Ceph commands are available in the bin/ directory. For example:

./bin/rbd create foo --size 1000
./bin/rados -p foo bench 30 write

To shut down the test cluster, run the following command from the build/ directory:

../src/stop.sh

Use the sysvinit script to start or stop individual daemons:

./bin/init-ceph restart osd.0
./bin/init-ceph stop

Running unit tests

To build and run all tests (in parallel using all processors), use ctest:

cd build
ninja
ctest -j$(nproc)

(Note: Many targets built from src/test are not run using ctest. Targets starting with "unittest" are run in ninja check and thus can be run with ctest. Targets starting with "ceph_test" can not, and should be run by hand.)

When failures occur, look in build/Testing/Temporary for logs.

To build and run all tests and their dependencies without other unnecessary targets in Ceph:

cd build
ninja check -j$(nproc)

To run an individual test manually, run ctest with -R (regex matching):

ctest -R [regex matching test name(s)]

(Note: ctest does not build the test it's running or the dependencies needed to run it)

To run an individual test manually and see all the tests output, run ctest with the -V (verbose) flag:

ctest -V -R [regex matching test name(s)]

To run tests manually and run the jobs in parallel, run ctest with the -j flag:

ctest -j [number of jobs]

There are many other flags you can give ctest for better control over manual test execution. To view these options run:

man ctest

Building Ceph using Containers

Ceph now provides tools to build the code, run unit tests, or build packages from within an OCI-style container using Podman or Docker! This allows one to build code for distributions other than the one you have on your system, avoids the need to install build dependencies for Ceph on your local system and provides an opportunity to test builds on platforms that are not yet supported by the official build infrastructure. For more details see the container build document.

Building the Documentation

Prerequisites

The list of package dependencies for building the documentation can be found in doc_deps.deb.txt:

sudo apt-get install `cat doc_deps.deb.txt`

Building the Documentation

To build the documentation, ensure that you are in the top-level /ceph directory, and execute the build script. For example:

admin/build-doc

Reporting Issues

To report an issue and view existing issues, please visit https://tracker.ceph.com/projects/ceph.

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