Generally on NFS Client, how to detect the Mounted-Point is no more available or DEAD from Server-end, by using the Bash Shell Script?
Normally i do:
if ls '/var/data' 2>&1 | grep 'Stale file handle';
then
echo "failing";
else
echo "ok";
fi
But the problem is, when especially the NFS Server is totally dead or stopped, even the, ls
command, into that directory, at Client-side is hanged or died. Means, the script above is no more usable.
Is there any way to detect this again please?
"stat" command is a somewhat cleaner way:
statresult=`stat /my/mountpoint 2>&1 | grep -i "stale"`
if [ "${statresult}" != "" ]; then
#result not empty: mountpoint is stale; remove it
umount -f /my/mountpoint
fi
Additionally, you can use rpcinfo to detect whether the remote nfs share is available:
rpcinfo -t remote.system.net nfs > /dev/null 2>&1
if [ $? -eq 0 ]; then
echo Remote NFS share available.
fi
Added 2013-07-15T14:31:18-05:00:
I looked into this further as I am also working on a script that needs to recognize stale mountpoints. Inspired by one of the replies to "Is there a good way to detect a stale NFS mount", I think the following may be the most reliable way to check for staleness of a specific mountpoint in bash:
read -t1 < <(stat -t "/my/mountpoint")
if [ $? -eq 1 ]; then
echo NFS mount stale. Removing...
umount -f -l /my/mountpoint
fi
"read -t1" construct reliably times out the subshell if stat command hangs for some reason.
Added 2013-07-17T12:03:23-05:00:
Although read -t1 < <(stat -t "/my/mountpoint")
works, there doesn't seem to be a way to mute its error output when the mountpoint is stale. Adding > /dev/null 2>&1
either within the subshell, or in the end of the command line breaks it. Using a simple test: if [ -d /path/to/mountpoint ] ; then ... fi
also works, and may preferable in scripts. After much testing it is what I ended up using.
Added 2013-07-19T13:51:27-05:00:
A reply to my question "How can I use read timeouts with stat?" provided additional detail about muting the output of stat (or rpcinfo) when the target is not available and the command hangs for a few minutes before it would time out on its own. While [ -d /some/mountpoint ]
can be used to detect a stale mountpoint, there is no similar alternative for rpcinfo, and hence use of read -t1
redirection is the best option. The output from the subshell can be muted with 2>&-. Here is an example from CodeMonkey's response:
mountpoint="/my/mountpoint"
read -t1 < <(stat -t "$mountpoint" 2>&-)
if [[ -n "$REPLY" ]]; then
echo "NFS mount stale. Removing..."
umount -f -l "$mountpoint"
fi
Perhaps now this question is fully answered :).