Xsan is Apple's storage area network or SAN for macOS. It allows multiple workstations to access shared storage over a network. Once connected, the computers on the network can read and write to the same storage system at the same time.
Workstations on Xsan will have access to metadata controller software, file system client software as well as management and monitoring tools.
Xsan is just like any other enterprise shared storage system. It can support large files and file systems, mounted files, metadata controller failover for fault tolerance and supports multiple operating systems.
Xsan was launched in 2005 and the last version, Xsan 5 was released in 2016.