Extending Ceph

You can extend Ceph by creating shared object classes called ‘Ceph Classes’. Ceph loads .so classes stored in the osd class dir directory dynamically (i.e., $libdir/rados-classes by default). When you implement a class, you can create new object methods that have the ability to call the native methods in the Ceph Object Store, or other class methods you incorporate via libraries or create yourself.

On writes, Ceph Classes can call native or class methods, perform any series of operations on the inbound data and generate a resulting write transaction that Ceph will apply atomically.

On reads, Ceph Classes can call native or class methods, perform any series of operations on the outbound data and return the data to the client.

See src/objclass/objclass.h, src/fooclass.cc and src/barclass for exemplary implementations.

Summary

Ceph Storage Clusters are dynamic--like a living organism. Although many storage appliances do not fully utilize the CPU and RAM of a typical commodity server, Ceph does. From heartbeats, to peering, to rebalancing the cluster or recovering from faults, Ceph offloads work from clients (and from a centralized gateway which doesn’t exist in the Ceph architecture) and uses the computing power of the OSDs to perform the work. When referring to Hardware Recommendations and the Network Config Reference, be cognizant of the foregoing concepts to understand how Ceph utilizes computing resources.

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