NFS client with stale inode data

The NFS client may have stale inode data due to caching and the course of action to be followed to correct this issue.

For performance reasons, some NFS implementations cache file information on the client. Some of the information (for example, file state information such as file size and timestamps) is not kept up-to-date in this cache. The client may view stale inode data (on ls -l, for example) if exporting a GPFS file system with NFS. If this is not acceptable for a given installation, caching can be turned off by mounting the file system on the client using the appropriate operating system mount command option (for example, -o noac on Linux® NFS clients).

Turning off NFS caching will result in extra file systems operations to GPFS, and negatively affect its performance.

The clocks of all nodes in the GPFS cluster must be synchronized. If this is not done, NFS access to the data, as well as other GPFS file system operations, may be disrupted. NFS relies on metadata timestamps to validate the local operating system cache. If the same directory is either NFS-exported from more than one node, or is accessed with both the NFS and GPFS mount point, it is critical that clocks on all nodes that access the file system (GPFS nodes and NFS clients) are constantly synchronized using appropriate software (for example, NTP). Failure to do so may result in stale information seen on the NFS clients.