Scenario: using SSHFS mounts from laptop to a central server, the SSHFS mount is broken after a longer disconnect (e.g. during suspend), causing the underlying SSH connection to time out.
Use -o reconnect,ServerAliveInterval=15,ServerAliveCountMax=3
The combination ServerAliveInterval=15,ServerAliveCountMax=3 causes the I/O errors to pop out after one minute of network outage. This is important but largely undocumented. If ServerAliveInterval option is left at default (without the alive check), processes which experience I/O hang seem to sleep indefinitely, even after the sshfs gets reconnected.
In other words what happens on -o reconnect without assigning ServerAliveInterval is that any I/O will either succeed, or hang the application indefinitely if the ssh reconnects underneath. A typical application becomes entirely hung as a result. If you'd wish to allow I/O to return an error and resume the application, you need ServerAliveInterval=1 or greater.
The ServerAliveCountMax=3 is the default anyway, but I like to specify it for readability.
fstab entry example for laptop, automount after network available:
nuc:/ /media/kodi fuse.sshfs reconnect,ServerAliveInterval=15,ServerAliveCountMax=3,auto,users,_netdev,x-systemd.after=network-online.target 0 0