NSS on Linux supports the O_NOATIME option for the Linux open API command. Support for the open API was added in a July 2006 patch to the the km_nss module of SUSE Linux Enterprise Server.
By default, the open command updates the access time whenever a file is opened. The O_NOATIME option disables the updating of access time, so that reading a file does not update its access time. Using this option allows you to back up a volume without modifying the access times ( ATIME) of its files.
The man page for the open(2) command defines the option as follows:
For information about how to use the O_NOATIME option, see the man page for the Linux open(2) command (enter man 2 open at a terminal console prompt).
Future patches to the km_nss module will incrementally add support for using the O_NOATIME option for the open command on the command line. For example, the patch released in September 2006 supports the O_NOATIME option when opening directories so that the access time is not modified when enumerating directories. Future patches will add support for using it at the system, volume, or file level.
Currently, NSS does not support the /etc/fstab and mount options called NOATIME. All of these NOATIME options have the same objective--that is, to prevent the access time from being updated unless the access involves file modification. Future patches to the km_nss module will incrementally add support for using the O_NOATIME option for the open command on the command line, /etc/fstab, and mount.
For the latest patches for the km_nss module, visit the Novell Support SUSE Patch Support Database (by date listing) .