Looking at the architecture, there are two major differences:<p>* XtreemFS has POSIX file system semantics and split-brain safe quorum replication for file data. With Quobyte, we pushed that further and have now full fault tolerance for all parts of the system, working at high performance for both file and block workloads (Quobyte also does erasure coding). GlusterFS replication is not split brain safe, and there are many failure modes that can corrupt your data.<p>* XtreemFS and Quobyte have metadata servers. This allows them place data for each file individually as it can store the location of the data. With Quobyte we pushed this quite far and have a policy engine that allows you configuring placement. When the policy is changed, the system can move file data transparently in the background. This way you can configure isolation, partitioning and tiering. GlusterFS has a pretty static assignment of file data to devices.