Some PFSes can handle multiple concurrent connections for update. They can manage the serialization of such requests. Such file systems are called sysplex aware for update. Most network file systems have this capability. NFS Client is one such file system type.

For a read/write mount to NFS Client, each system in the shared file system group will make a direct connection to NFS. The first system to make such a connection is still called the file system owner. All subsequent systems to make a direct connection are considered non-owners, rather than clients. This type of multiple direct connection for read/write access allows for maximum I/O performance by eliminating the need to send requests to the file system owner.

However, sometimes a non-owning system cannot make a direct connection to the PFS even after meeting the minimum requirements (for example, sometimes requests to NFS Client time out before they are satisfied). That system might be given a cross-system messaging connection, making it a client to the file system. While this is not the optimal mount mode for this type of file system, it does allow access to the file system.