Crystal enables administrators to write SDS policies in a "If-This-Then-Than" (IFTTT) form via a DSL. These policies can change the behavior of the system by enforcing storage filters ("That"). The enforcement of filters may be static or dynamic ("This"). A user-friendly dashboard enables administrators to write policies and control the system.
The "This" part of Crystal's IFTTT-like policies refers to introspective information. Crystal enables to define dynamic policies based on monitoring information and the metadata of object requests. Moreover, inspection metrics can be plugged-in and exposed to the DSL at runtime.
In Crystal's IFTTT-like policies "That" means storage filters. Crystal enables administrators to transparently intercept object requests with storage filters. Besides, developers can implement many types of storage filters, ranging from storage management techniques to performance control.
Web site: http://crystal-sds.org/