Defined Mutation: A region is defined if the clients can see what mutation has written in its entirety, even if it is in more than one block. For example if A and B are writing concurrently. the client can see only the mutation of A or the Mutation of B, not a part of each other.
Consistent: all the clients can see the same data
File and chunk namespaces: A b-tree that kind of mimics a directory.
NOTE: During writes:
