+<div class="mainsegment">
+ <h3>We are hiring!</h3>
+ <div>
+Ceph is actively seeking experienced C/C++ and Linux kernel developers who are interested in helping turn Ceph into a stable production-grade storage system. Competitive salaries, benefits, etc. If interested, please contact sage at newdream dot net.
+ </div>
+</div>
+
<div class="mainsegment">
<h3>Welcome</h3>
<ol>
<li><b>Petabyte-scale storage</b> -- Ceph is built from the ground up to seamlessly and gracefully scale from gigabytes to petabytes and beyond. Scalability is considered in terms of workload as well as total storage. Ceph is designed to gracefully handle workloads in which tens thousands of clients or more simultaneously access the same file, or write to the same directory--usage scenarios that bring typical enterprise storage systems to their knees.
- <li><b>Robust, open-source distributed storage</b> -- Ceph is released under the terms of the LGPL, which means it is free software (as in speech). Ceph will provide a variety of key features that are sorely lacking from existing open-source file systems, seamless scalability (the ability to simply add disks to expand volumes), intelligent load balancing, and snapshot functionality.
+ <li><b>Robust, open-source distributed storage</b> -- Ceph is released under the terms of the LGPL, which means it is free software (as in speech). Ceph will provide a variety of key features that are sorely lacking from existing open-source file systems, including seamless scalability (the ability to simply add disks to expand volumes), intelligent load balancing, content-addressable storage (CAS), and snapshot functionality.
</ol>
Here are some of the key features that make Ceph different from existing file systems that you may have worked with:
<div class="mainsegment">
- <h3>Roadmap</h3>
+ <h3>Current Roadmap</h3>
<div>
Here is a brief summary of what we're currently working on, and what state we expect Ceph to take in the foreseeable future. This is a rough estimate, and highly dependent on what kind of interest Ceph generates in the larger community.
<ul>
- <li><b>Q4 2006</b> -- MDS recovery for single MDS configurations.
- <li><b>Q1/Q2 2007</b> -- MDS recovery for multi-MDS configurations.
- <li><b>Q2 2007</b> -- Snapshots.
+ <li><b>Q2 2007</b> -- MDS recovery for multi-MDS configurations.
+ <li><b>Q3 2007</b> -- Distributed monitors.
+ <li><b>Q4 2007</b> -- Snapshots.
</ul>
</div>
<h3>Tasks</h3>
<div>
- Although Ceph is currently a working prototype that demonstrates the key features of the architecture, a variety of
key features need to be implemented in order to make Ceph a stable file system that can be used in production environments. Some of the key tasks are outlined below. If you are a kernel or file system developer and are interested in contributing to Ceph, please join the email list and <a href="mailto:ceph-devel@lists.sourceforge.net">drop us a line</a>.
+ Although Ceph is currently a working prototype that demonstrates the key features of the architecture, a variety of
features need to be implemented in order to make Ceph a stable file system that can be used in production environments. Some of these tasks are outlined below. If you are a kernel or file system developer and are interested in contributing to Ceph, please join the email list and <a href="mailto:ceph-devel@lists.sourceforge.net">drop us a line</a>.
<p>
<h4>Snapshots</h4>
<div>
-
+ The distributed object storage fabric (RADOS) includes a simple mechanism of versioning files, and performing copy-on-write when old objects are updated. In order to utilize this mechanism for implementing flexible snapshots, the MDS needs to be extended to manage versioned directory entries and maintain some additional directory links. For more information, see <a href="http://www.soe.ucsc.edu/~sage/papers/290s.osdsnapshots.pdf">this tech report</a>.
+ </div>
+
+ <h4>Content-addressable Storage</h4>
+ <div>
+ The underlying problems of reliable, scalable and distributed object storage are solved by the RADOS object storage system. This mechanism can be leveraged to implement a content-addressible storage system (i.e. one that stores duplicated data only once) by selecting a suitable chunking strategy and naming objects by the hash of their contents. Ideally, we'd like to incorporate this into the overall Ceph file system, so that different parts of the file system can be selectively stored normally or by their hash. Ideally, the system could (perhaps lazily) detect duplicated data when it is written and adjust the underlying storage strategy accordingly in order to optimize for space efficiency or performance.
</div>
<h4>Ebofs</h4>
The prototype Ceph client is implemented as a user-space library. Although it can be mounted under Linux via the <a href="http://fuse.sourceforge.net/">FUSE (file system in userspace)</a> library, this incurs a significant performance penalty and limits Ceph's ability to provide strong POSIX semantics and consistency. A native Linux kernel implementation of the client in needed in order to properly take advantage of the performance and consistency features of Ceph. Because the client interaction with Ceph MDS and OSDs is more complicated than existing network file systems like NFS, this is a non-trivial endeavor. We are actively looking for experienced kernel programmers to help us out!
</div>
- <h4>CRUSH tool</h4>
+ <h4>CRUSH tools</h4>
<div>
Ceph utilizes a novel data distribution function called CRUSH to distribute data (in the form of objects) to storage nodes (OSDs). CRUSH is designed to generate a balanced distribution will allowing the storage cluster to be dynamically expanded or contracted, and to separate object replicas across failure domains to enhance data safety. There is a certain amount of finesse involved in properly managing the OSD hierarchy from which CRUSH generates its distribution in order to minimize the amount of data migration that results from changes. An administrator tool would be useful for helping to manage the CRUSH mapping function in order to best exploit the available storage and network infrastructure. For more information, please refer to the technical paper describing <a href="publications.html">CRUSH</a>.
</div>
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