Hello Peter and thank you for your answer.  > Do the file and the enclosing directory have ACLs set? (check on the Isilon with ls -le)  No, we actually noticed that none of the ACLs set with nfs4_stefacl were carried  to the Isilon side.  > Does nfs4_getfacl return something consistent with either the ACLs or Unix bits (whatever applies)?  nfs4_getfacl only reports Unix bits.  We finally found what was the misconfiguration. We have recently upgraded from 7.1.1.9 to 8.0.0.2. During this migration the configuration parameter enabling the use of NFSv4 ACLs seems to have been reset.  We then had to modify the "General ACL Settings". For sure, why did not we think about this before? Probably because the configuration parameter is "Allow ACLs to be created through SMB".  After some echanges with the support team, it seems that this parameter should be interpreted "Allow ACLs to be created through SMB and NFSv4" and not only SMB. Peharps the label of this configuration parameter should be modified in the future to clarify the feature.  NFSv4 ACL is again working properly and we are again Isilon happy users.  Thank you again Peter for taking the time to respond, we hope that these exchanges will help others in the future.  Cheers! Benoit  
Is there anybody accessing an ISILON cluster running OneFS 8.0.0.4 from RHEL6 or 7 NFSv4 clients ?   We are experiencing some issues with ACLs on the client side. We are able to mount and access NFSv4 exports without any problem, but we are not able to make NFSv4 ACL working properly. The command "nfs4_setfacl" runs silently and does not report any error (no error message and return code is 0).  The ISILON export is of course mounted by the NFSv4 client with the options "nfsvers=4,acl,sec=sys".  More generally, is there a documentation or a guide describing how to configure NFSv4 for both the ISLON cluster and Linux clients ? 
ISILON 8.0.4, RHEL[6,7] NFSv4 clients and ACL not working properly.