Some open source distributed storage solutions, some bigger than others:
- Sheepdog: a project which has matured lately. It has iSCSI support with multi-path for non linux systems, and agents for linux based systems.
- Open vStorage: Open vStorage is the best Storage Platform for Advanced Storage Workloads: Virtualization, vDisks, Docker, Databases, NAS, SAN ...
- Ceph: Ceph is a distributed object store and file system designed to provide excellent performance, reliability and scalability.
- Tahoe-LAFS: decentralized cloud storage system