NFS connection disappear

[Maxim Yakimenko]

Collegues, I found interesting thing:

I have NFS-server on Linux RH AS 3 and client - HPUX 11.23
I've created script to monitor connection
I use cron to run script that check this connection by command
"netstat -an |grep $HOST.2049|grep ESTAB|wc -l"
where $HOST - is IP of server
And sometimes I receive mail that there is no connection with this server. On client I manualy do

"netstat -an |grep $HOST"

and it returns nothing

then I do "bdf"

And again "netstat -an |grep $HOST"
It returns string with established connection.
In logs of NFS-server I see no records about mount authorization of this client.

What is the mystery? Or NFS turns off connection when no traffic are carried over it and then reestablish it when needed with reauthorization?

[Maxim Yakimenko]

I used tcpdump to see what happens -
Yes, connection is closed after 15 minutes if it is not used, and when I do bdf server and client do some communication and connection is established again.
So questuion need to be reformerd to - how to make connection permanent regardless if it used or not? I use hard mount, so doing bdf before

[Peter Godron]

Hi,
it depends on how you control your nfs mounting. If you go via the automount your suggestion with connection being turned off if there is no traffic is absolutlely correct.

Either use hard/soft mounted connections or send regular 'heartbeats' (ls/bdf..)

Please also read:
http://forums1.itrc.hp.com/service/forums/helptips.do?#33
on how to reward any useful answers given to your questions.

[Maxim Yakimenko]

Mount is hard, it is written in /etc/fstab on client - is there any other option? I thought about heartbeat, but heartbeat in form of bdf can hang if NFS problem exists. So what to do?