[CentOS] how does autofs deal with stuck NFS mounts and suspending to RAM?

Mon May 18 11:13:50 UTC 2020
hw <hw at gc-24.de>

Hi,

after trying sshfs to mount a remote file system on a server with the result 
that sshfs will sooner or later get stuck and require a reboot of the client, 
I'm fed up with it and am looking for alternatives.

So next I would like to use NFS over a VPN connection instead.  To minimize 
the instances of the NFS mount getting stuck, it might be helpful to use 
autofs.

What happens when the mount is stuck because the connection is down and autofs 
figures the idle timeout has expired and tries to unmount the remote file 
system?

What happens when I put the client to sleep by suspending to RAM?  Will autofs 
automatically unmount first, or will the server have to deal with a client 
that has apparently gone away and might re-appear later in unexpected ways?

Is there a way to tell NFS to retry an operation _now_ after the connection 
went down and came back, rather than having to wait for a possibly rather long 
time?

Is there a better alternative for mounting remote file systems over unreliable 
connections?