We have nine nfsv3 client systems (Debian wheezy) and two NFS servers (EMC VNX). The clients each mount about 50 nfs filesystems off each nfs server. We are trying to squeeze more performance out of the NFS client systems. Recently I have noticed that there appears to be only one TCP connection to each NFS server. I am wondering if this single TCP connection is a performance bottleneck with lots of NFS mounts to the same NFS server and whether there is a way to increase the number of TCP connections on the Debian NFS client to each NFS server. On Solaris there is the parameter below:
rpcmod:clnt_max_conns - sets how many concurrent TCP connections the system is able to use to a single NFS server.
I am wondering if this is a problem and whether there is something similar on Debian or any other Linux version? We did use NFSv4 previously but had to revert back to NFSv3 due to performance issues. We may look at NFSv4 again if that performs better.