Hybris is a key-value hybrid cloud storage system that robustly replicates data
over untrusted public clouds while keeping metadata on trusted private premises.
Thanks to this design, Hybris provides strong consistency guarantees (i.e., linearizability) and affordable Byzantine fault tolerance (i.e., withstanding f faulty clouds with as few as 2f+1 replicas).
Hybris is also very efficient: in the common case it writes to f+1 clouds and it reads from one single cloud.
Code base overview
The code base of Hybris is composed by two main modules: MdsManager and KvsManager; the first is a thin wrapper layer of the metadata distributed storage service (i.e. ZooKeeper or Consul), while KvsManager implements the storage primitives towards the APIs of the main public cloud storage services - currently, it supports Amazon S3, Google Cloud Storage, Rackspace Cloud Files and Windows Azure Blob.
Maven is used to compile the code and manage the dependencies.
Read the wiki for more information on development setup.