The detail here that this only happens with 100GB+ file sizes is an interesting one.  I can certainly imagine that this would take a long time to complete the testing with that much transfer.  I assume there is a workflow that is regularly transferring files of this size that this has become an issue?   I will highly recommend working with your account team to renew the support for your Isilon hardware - you really are missing a lot of great new things without the support.   With files of that size, I wonder if there isn't a better way to transfer that would offer the reliability you seek.  I certainly don't know why an NFS connection would not be reliable, but at that size, there could be further options to take advantage of.  I'm thinking packaging the file as a tar ball, then transferring?  Using FTP instead of NFS?  I will admit this line of thinking is a bit of wild speculation - but my instinct is that with this file size, there may be something in this version of NFS transfers that reduces the stability.  No information to back that up, just a gut feel that I'd have to research further, but does support what you are saying. 
Hi everyone,  I would like to share an issue we encountered from months.  While we copy a file through nfs and we compare md5, it could happen they are not the same. It results with drop when this file is a video file for example. The same copy through samba works (same md5) but is muuuuch longer.  I'm just wondering if one of you would know the “room for manoeuvre” I have with nfs parameters to try to resolve this issue. I am, of course, at your disposal if someone need additional information (setup, cli results, etc.)  Every ideas, tracks, magic potion are welcome [IMAGE]  Thank you for your precious help  Best,  Pierre   isi-tvs-1-1# isi version Isilon OneFS v6.5.5.10 B_6_5_5_138(RELEASE): 0x605050000A0008A:Mon Aug 27 16:20:22 PDT 2012    root[NAME]-02.west.isilon.com:/build/mnt/obj.RELEASE/build/mnt/src/sys/IQ.amd64.release  [IMAGE]  Computer for copying are Apple computer. Several macOS > same issue (from 10.6.8 to 10.10.2) NFS chosen for performance in comparison with samba.  For some macs, we follows Isilon considerations regarding nfs, namely : nfs.client.mount.options=nfssvers=3,tcp,async,nolock,rw,rdirplus,rsize=65536,wsize=65536 net.tcp.delayed_ack=0 net.inet.tcp.recvspace=131072 net.inet.tcp.sendspace=131072  For some others, freshly reinstalled, we don’t. Whatever theses parameters, the issue comes, randomly, most often on big files.  NB : nfs copy run and finishe without error
NFS copy issue - source and dest. are differents