Issue

There are several RHEL servers that function as NFS servers and they all have the similar issue. After a period of time, the NFS clients start to experience very slow performance, and commands like ls -l on the NFS file systems (on the NFS clients) hang for a long period before returning. This apparently only happens when I/0 is occurring to the NFS file system on that client. If we stop the process doing the I/O (usually Oracle RMAN backups), the ls -l performance is fine. The problem returns when I/O is resumed. Restarting the NFS server service on the RHEL NFS server resolves the problem for a while.