We are have a few NFS mounts accessible from two different Vmware clusters and several windwos machines.
I can write files to the NFS mounts from my vsphere 4.0u2 cluster with no problem.
I can write files from the windows machines.
However, with esxi 4.1, if I try to write a file of any real size (over a couple meg) I get an error: "Error caused by file:datastore/filepath/filename"
Small files seem to copy ok.
I tried increasing the timeout values as per the vsphere/nfs best practice guide but this did not seem to help.
Besides the version of vsphere there is another notable difference.
the ESXi 4.0u2 cluster is using vmware dvswtiches with 1gb nics.
the ESXi 4.1 cluster is using nexus 1000v swtiches with a 10gb trunk.