How Software Designed Storage works
The Ceph and Gluster storage software handles the co-ordination of data access and placement across a pool of servers, ensuring that clients have a highly-available and co-ordinated method of access and that data is replicated reliably across the infrastructure. The software handles the failure of individual disks, nodes, racks and sites in a configurable manner to ensure data availability within the constraints you define.
Ceph offers block, file and object storage interfaces to consume the distributed storage. Block, File and Object capabilities can be augmented with iSCSI, SMB, NFS and S3-compliant gateway technology to make the storage visible to non-Linux consumers where required.
Gluster offers a predominantly file-based storage interface which can be exposed either natively on Linux or through SMB or NFS to non-Linux consumers.
Being some of the more popular Open Source distributed storage systems, Ceph and Gluster have integrations with many other systems such as KVM/QEMU, OpenNebula and Kubernetes that can orchestrate storage provisioning and management.