NFS performance: How to track down a bad UNIX or Linux host

In NFS environments, it is possible to see sluggish performance for a single client, or subset of clients.
This article discusses the different methods for troubleshooting client NFS performance for 7-mode and Clustered Data ONTAP.
7-mode: The command ‘nfsstat’ can be used to obtain statistics regarding NFS clients.
- This requires per-client statistics to be enabled, which entails some performance overhead.
- Therefore, these statistics are not as beneficial when the performance impact experienced is wide-reaching, as it could make the problem worse.
- For a smaller number of clients, the overhead is usually insignificant.
  - To enable per-client statistics:

> options nfs.per_client_stats.enable on

Clustered Data ONTAP does not provide per-client NFS statistics.
As of ONTAP 9, the ‘statistics top’ family of commands exists to provide a list of top clients, or top files. Therefore, troubleshooting a poor performing client with Clustered Data ONTAP requires a bit of finesse.