System hangs on shutdown if Windows network drive in fstab

This is a well known bug : https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/211631?comments=all

It's one of those thankfully-rare, but nonetheless embarrassing, high impact, over-two-years-old bugs that negatively impact Ubuntu's sheen.

It should only affect WIFI connections, but I don't see any detail about that in your question. If you're experiencing this over a wired connection then something else is in play here.

Until Network Manager is fixed (it shuts down wifi connections too quickly - before any of the init scripts are triggered), the only feasible workaround I could find is to use AutoFS.

Paraphrased from http://www.howtoforge.com/accessing_windows_or_samba_shares_using_autofs

sudo apt-get install autofs

Create /etc/auto.cifs with these file contents :

#!/bin/bash
# $Id$
# This file must be executable to work! chmod 755!
key="$1"
# Note: create a cred file for each windows/Samba-Server in your network
#       which requires password authentification.  The file should contain
#       exactly two lines:
#          username=user
#          password=*****
#       Please don't use blank spaces to separate the equal sign from the
#       user account name or password.
credfile="/etc/auto.smb.$key"
# Note: Use cifs instead of smbfs:
mountopts="-fstype=cifs,file_mode=0644,dir_mode=0755,uid=user,gid=users"
smbclientopts=""
for P in /bin /sbin /usr/bin /usr/sbin
do
        if [ -x $P/smbclient ]
        then
                SMBCLIENT=$P/smbclient
                break
        fi
done
[ -x $SMBCLIENT ] || exit 1
if [ -e "$credfile" ]
then
        mountopts=$mountopts",credentials=$credfile"
        smbclientopts="-A "$credfile
else
        smbclientopts="-N"
fi
$SMBCLIENT $smbclientopts -gL $key 2>/dev/null \
   | awk -v key="$key" -v opts="$mountopts" -F'|' -- '
        BEGIN   { ORS=""; first=1 }
    /Disk/  { if (first) { print opts; first=0 };
          gsub(/ /, "\\ ", $2);
          sub(/\$/, "\\$", $2);
          print " \\\n\t /" $2, "://" key "/" $2 }
        END     { if (!first) print "\n"; else exit 1 }
        '

(edit the mountops line to reflect your real user name)

Make it exectuable with sudo chmod 755 /etc/auto.cifs

Then add this line to your /etc/auto.master, at the bottom :

/smb /etc/auto.cifs --timeout=60 --ghost

Finally, restart autofs with this line (or a reboot would work, of course) :

sudo service autofs restart

And you should then be able to open nautilus to /smb/server/share (or ls -l /smb/Server/Share)

Shutdown, suspend, hibernate should all be seamless.

If you use passwords to connect to your shares, you have to add another file in /etc/ for each server you connect to, with username and password specified. Do a "man autofs" for more detail on that, but here's the gist :

You need one credentials file for each password-protected share that you're connecting to. In your case, your server is called "Server", so create the relevant file with gksudo gedit /etc/auto.smb.Server. Then put this into that file :

username=myusername
password=mypassword

(obviously editing the fields as required).

Then you'll need to make sure that this file is only readable by root with sudo chmod 600 /etc/auto.smb.Server.

Then restart autofs as above and try browsing /smb/Server - you should see a list of your shares.

If you connect using an IP address, you'll need to repeat this process for /etc/auto.smb.192.168.1.10 or whatever.

You should use the guide which shows you how to make an unmount shutdown script and make sure that it's still switch on. Upgrades or updates could theoretically have knocked it off it's perch. Check that your script is in /etc/rc0.d and that it's named S01smb_umount or similar so it runs as the first order of business.

Otherwise you may end up with it unmounting the samba drive normally (waiting, waiting) and then running your script. Which would do nothing.

I had the same problem with a Win2003 server samba share and following this guide fixed the problem.