Ceph

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Ceph
Ceph logo.jpg
Developer(s) Sage Weil, Yehuda Sadeh Weinraub, Gregory Farnum
Stable release 0.42 / February 20, 2012; 8 days ago (2012-02-20)
Operating system Linux
Type Distributed file system
License LGPL
Website ceph.newdream.net

Ceph is a free software distributed file system initially created by Sage Weil. Ceph's main goals are to be POSIX-compatible, and completely distributed without a single point of failure. The data is seamlessly replicated, making it fault tolerant.[1]

Clients mount the file system using a Linux kernel client. On March 19, 2010, Linus Torvalds merged the Ceph client for Linux kernel 2.6.34[2] which was released on May 16, 2010. An older FUSE-based client is also available. The servers run as regular Unix daemons.

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[edit] History

Ceph was initially created by Sage Weil (developer of the Webring concept and co-founder of DreamHost) for his doctoral dissertation[3], which was advised by Professor Scott A. Brandt in the Jack Baskin School of Engineering at the University of California, Santa Cruz and funded by the DOE/NNSA involving LLNL, LANL, and Sandia National Laboratories.

After his graduation in fall 2007, Weil continued to work on Ceph full time, and the core development team expanded to include Yehuda Sadeh Weinraub and Gregory Farnum.

[edit] Design

Ceph employs three distinct kinds of daemons:

  • Cluster monitors (ceph-mon), which keep track of active and failed cluster nodes.
  • Metadata servers (ceph-mds) which store the metadata of inodes and directories.
  • Object storage devices (ceph-osds) which actually store the content of files. Ideally, OSDs store their data on a local btrfs filesystem, though other local filesystems can be used instead.[4]

All of these are fully distributed, and may run on the same set of servers. Clients directly interact with all of them.[5]

Ceph does striping of individual files across multiple nodes to achieve higher throughput, similarly to how RAID0 stripes partitions across multiple hard drives. A planned extension to this feature is adaptive load balancing, whereby frequently accessed objects are replicated over more nodes.[5]

[edit] Etymology

The name "Ceph" is a common nickname given to pet octopus and derives from cephalopods, a class of molluscs, and ultimately from Ancient Greek κεφαλή (kephalē), meaning "head". The name (emphasized by the logo) suggests the highly parallel behavior of an octopus and was chosen to connect the file system with UCSC's mascot, a banana slug called "Sammy"[6]. Banana slugs are gastropods which are also a class of molluscs.

[edit] See also

[edit] References

[edit] Further reading

[edit] External links

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