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101 lines
3.2 KiB
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101 lines
3.2 KiB
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=================
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Welcome to Ceph
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=================
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Ceph is a distributed network storage and file system with distributed
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metadata management and POSIX semantics.
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RADOS is a reliable object store, used by Ceph, but also directly
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accessible.
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``radosgw`` is an S3-compatible RESTful HTTP service for object
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storage, using RADOS storage.
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RBD is a Linux kernel feature that exposes RADOS storage as a block
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device. Qemu/KVM also has a direct RBD client, that avoids the kernel
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overhead.
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.. image:: overview.png
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Mailing lists, bug tracker, IRC channel
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=======================================
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- `Ceph Blog <http://ceph.newdream.net/news/>`__: news and status info
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- The development mailing list is at ceph-devel@vger.kernel.org, and
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archived at Gmane_. Send email to subscribe_ or unsubscribe_.
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- `Bug/feature tracker <http://tracker.newdream.net/projects/ceph>`__:
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for filing bugs and feature requests.
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- IRC channel ``#ceph`` on ``irc.oftc.net``: Many of the core
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developers are on IRC, especially daytime in the US/Pacific
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timezone. You are welcome to join and ask questions. You can find
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logs of the channel `here <http://irclogs.ceph.widodh.nl/>`__.
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- `Commercial support <http://ceph.newdream.net/support/>`__
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.. _subscribe: mailto:majordomo@vger.kernel.org?body=subscribe+ceph-devel
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.. _unsubscribe: mailto:majordomo@vger.kernel.org?body=unsubscribe+ceph-devel
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.. _Gmane: http://news.gmane.org/gmane.comp.file-systems.ceph.devel
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Status
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======
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The Ceph project is currently focusing on stability. Users are
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welcome, but we do not recommend storing valuable data with it yet
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without proper precautions.
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As of this writing, RADOS is the most stable component, and RBD block
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devices are fairly reliable, if not performance tuned yet. The OSD
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component of RADOS relies heavily on the stability and performance of
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the underlying filesystem, and we keep hearing reports of ``btrfs``
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issues; while on the long term we believe in ``btrfs``, in the short
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term you may wish to carefully consider the tradeoffs between ``ext4``
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and ``btrfs``, and make sure you are running the latest Linux kernel.
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Radosgw is still going through heavy development, but it will likely
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mature next.
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.. _cfuse-kernel-tradeoff:
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The Ceph filesystem is functionally fairly complete, but has not been
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tested well enough at scale and under load yet. Multi-master MDS is
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still problematic and we recommend running just one active MDS
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(standbys are ok). If you have problems with ``kclient`` or ``ceph-fuse``,
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you may wish to try the other option; in general, ``kclient`` is
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expected to be faster (but be sure to use the latest Linux kernel!)
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while ``ceph-fuse`` provides better stability by not triggering kernel
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crashes.
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As individual systems mature enough, we move to improving their
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performance (throughput, latency and jitter). This work is still
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mostly ahead of us.
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Ceph is developed on Linux. Other platforms may work, but are not the
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focus of the project. Filesystem access from other operating systems
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can be done via NFS or Samba re-exports.
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Table of Contents
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=================
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.. toctree::
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:maxdepth: 3
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start/index
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architecture
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ops/index
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rec/index
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config
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api/index
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Internals <dev/index>
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man/index
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papers
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appendix/index
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Indices and tables
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==================
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- :ref:`genindex`
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