This is a problem that has existed for me since FreeBSD 10.3-RELEASE and I posted on that topic here on the forum and opended a bug on this about a year ago.
The bug is still open, which is no wonder. A year ago I was totally wrong about the cause; I thought it was a autofs/autounmountd problem.
In short:
Since then I have learned a lot while debugging autofs and NFS and looking into the rc system (without fully understanding it honestly).
Another approach is to simply remove nfs_client_enable="YES" from /etc/rc.conf to prevent it from executing
The problem exists without the use of autofs as well, it was just helpfull while debugging.
Manually mounted NFS mounts or via /etc/fstab show the same missing rpc call when the
client is shut down. Only manually executing
All this can easily be cleaned up by executing
and it is what I do. To successfully use autofs with NFS I run
The problem lies in NFS though, not in autofs.
After spending so much debugging that (for a while on two dedicated machines client/server), reading and learning about NFS and the rc system I'm still a little in doubt that something so well established like NFS could be broken.
This started on FreeBSD 10.3-RELEASE and does still exist on 11.2-RELEASE-p3.
What do you think?
The bug is still open, which is no wonder. A year ago I was totally wrong about the cause; I thought it was a autofs/autounmountd problem.
In short:
Since then I have learned a lot while debugging autofs and NFS and looking into the rc system (without fully understanding it honestly).
- When a NFS client is shut down, the NFS server does not get notified.
showmountandcat /var/db/mountdtab(on the NFS server) shows the server still thinks the client is connected. When shutting down a client, there seems to be missing arpc.umntallcall. - Goes easily undetected. When client boots, from /etc/rc.d/nfsclient, the missing
rpc.umntall -kcall is executed, which then removes the clients /var/db/mounttab and notifies the NFS server. - Using autounmountd was helpful in debugging, since it can remove mounts from the kernel without calling
rpc.umntall -kitself. Shows right away the rpc call is missing.
automount -u (or simply wait for autounmountd) to disconnect the automounted NFS mounts and then again automounting a NFS mount, will grow the /var/db/mount(d)tab both on the client on the server with identical entries. That doesn't keep NFS from working in any way, though.Another approach is to simply remove nfs_client_enable="YES" from /etc/rc.conf to prevent it from executing
rpc.umntall -k on boot. This will show that there hasn't been any rpc call when the client was shut down, as the mount entries on the client and the server are still present after the clients reboot.The problem exists without the use of autofs as well, it was just helpfull while debugging.
Manually mounted NFS mounts or via /etc/fstab show the same missing rpc call when the
client is shut down. Only manually executing
umount ... makes the neccessary rpc call to notify the NFS server of the disconnection. All this can easily be cleaned up by executing
rpc.umntall -k at any time on the clientand it is what I do. To successfully use autofs with NFS I run
rpc.umntall -k every hour from cron on I have added rpc.umntall to the very end of /etc/rc.shutdown.The problem lies in NFS though, not in autofs.
After spending so much debugging that (for a while on two dedicated machines client/server), reading and learning about NFS and the rc system I'm still a little in doubt that something so well established like NFS could be broken.
This started on FreeBSD 10.3-RELEASE and does still exist on 11.2-RELEASE-p3.
What do you think?