For the NFS version 3 WRITE procedure or NFS version 4 WRITE operation there is a processing argument stable and output parameter commit which specifies whether data received by a write request for a z/OS UNIX file object is committed to nonvolatile storage before the write response is returned to you.

If the stable processing argument is used during the write procedure, there are three modes when the write procedure writes to a file:

file_sync

The z/OS NFS server must commit all data written and all file system data to stable storage before returning commit results.

data_sync

The z/OS NFS server must commit all data written and sufficient metadata to enable retrieval of data, before it returns a reply to the client.

unstable

The z/OS NFS server may not commit any part of the data and metadata to stable storage, before returning a reply to the client. The data will be committed when a timeout occurs.

For the commit procedure, the z/OS server will support committing the entire data and metadata to stable storage.