This topic explains how to obtain time stamps for MVS data sets. For z/OS UNIX files, the time stamp is directly available from the underlying file system because it is saved as part of the file metadata.

UNIX file attributes define the following time stamps:

atime

The last time the file was accessed (read).

mtime

The last time the file was modified (write).

ctime

The last time the file status was changed (chmod).

The z/OS NFS server treats all MVS data sets as belonging to the same file system (having the same file system id). Since not all attributes are supported for all DFSMSdfp access methods, but the NFS protocols track attribute support at the file system level, the z/OS NFS server reports to the client that atime and mtime are supported for all MVS data sets. The z/OS NFS server will generate values as described in this topic.

The metatime attribute, which is new in NFS version 4, is not supported by any DFSMSdfp access method, nor by the z/OS NFS server. The new NFS version 4 change attribute will be based on mtime values as described in this topic.