RADOS class caveats

Although we have seen the power that can be harnessed using Ceph's RADOS classes, it's important to note that this is achieved by calling your own customized code from deep inside OSDs. As a consequence, great care needs to be taken that your RADOS class is bug free. A RADOS class has the ability to modify any data on your Ceph cluster, and so accidental data corruption is easily possible. It is also possible for the RADOS class to crash the OSD process. If the class is used in large-scale cluster operations, this has the ability to affect all OSDs in the cluster, so great care should be taken to ensure that error handling is done properly to avoid errors.