An often-overlooked feature of Ceph is the ability to load custom code directly into OSD, which can then be executed from within a librados application. This allows you to take advantage of the large distributed scale of Ceph to not only provide high-performance scale-out storage, but also to distribute computational tasks over OSDs to achieve mass parallel computing. This ability is realized by dynamically loading in RADOS classes to each OSD.

In this chapter, we will cover the following topics:

• Example applications and the benefits of using RADOS classes
• Writing a simple RADOS class in Lua
• Writing a RADOS class that simulates distributed computing