[NFS-Ganesha-Support] New to NFS Ganesha - seeking general info on tuning and benchmarking

Hi, We have a 2-node NFS ganesha cluster (using CTDB), that I recently inherited administration for. Most of our internal users are satisfied with the performance, but one particular user has had all sorts of performance related issues affecting their adoption and usage of the NFS shares. From initial analysis, this seems to be a problem of loading (because it occurs during intensive reads/writes of large datasets, such as during rsync transfers or backup reads). So far, I have not yet been able to establish whether the problem is due to the number of files or the volume of data, and I am now setting up test client nodes to try and reproduce the client's issues. I googled around seeking information on tuning (kernel, NFS, OS, etc), but cannot seem to find any at all. Please, can someone share some insight into how to go about trying to optimize the performance of ganesha. Also, would appreciate any insight /suggestion on how best to benchmark the performance. Thanks in advance