+** Layered architecture
++ layer 1 :: disk / block storage / partition
+
++ layer 2 :: key/value storage. Keys are unique and are dictated by
+ storage engine. Value is arbitrary but limited size byte
+ array. This layer is responsible for handling disk
+ defragmentation and consistency in case of crash
+ recovery.
+
++ layer 3 :: key/value storage. Keys are content hashes. Values are
+ arbitrary but limited size content byte arrays. This
+ layer effectively implements content addressable
+ storage. Content addressible storage enables GIT-like
+ behavior (possibility for competing branches, retaining
+ history, transparent deduplication)