We have a number of specialized workstations running CentOS 7.4 (kernel 3.10.0-693.11.1.el7.x86_64) that are both NFSv3 clients and servers- i.e. they can mount each other's exports via autofs - however, occasionally the mount process hangs Each workstation has 4 exports, 2 of the exports are subdirectories of the root disk - these are exported with the 'sync' option , the other 2 exports are the mount points of separate file systems - exported with the 'async' option. All are XFS file systems The mount process hang only happens with the exports from the root disk - and once a mount hangs on one of these exports, a mount of the other export from the root disk also hangs - but mounting the other 2 exports are fine The problem can occur on any of the workstations mounting any of the other workstations exports We can temporary fix the problem by running 'exportfs -f' on the server Running tcpdump on the client (or server) when attempting a mount when in this state shows that the client sends an FSINFO call, but doesn't get a reply - it then retransmits the FSINFO call and sends another FSINFO call about 18 seconds later - but no replies - which I'm guessing is significant? Unfortunately, it is not straight forward to upgrade the kernel on these workstations - so difficult to test if a newer kernel would fix the issue ... Is anyone able to suggest any other debugging steps we can take to find out what the issue might be? Thanks James Pearson
