So I wrote a little script, and put it in /etc/network/if-up.d/ named “jumbo-frames.sh”. The if-*.d/ structure is designed for exactly this purpose: run a script when an interface comes up. The basic premise is: If I’m plugged into a wired network (eth0) in the lab (domain or IP address match certain parameters), then set the MTU to 9000 (jumbo frame support), otherwise assume the network has a normal MTU (1500). This allows the system to reconfigure on the fly if I put it to sleep and go visit a customer.

Here’s the code:

#!/bin/sh
# Set support for jumbo frames when at home on wired network, else do not.
# Determine home network based on IP address and DNS-determined name.
# $IFACE should be set by the caller.

if [ "$DOM" = "$HOMED" ]; then
$IFC $IFACE mtu $MTU
elif [ "$NET" = "$HOMEN" ]; then
$IFC $IFACE mtu $MTU
else
$IFC $IFACE mtu $DEFMTU
fi


A sample securenets file might look like this:

# allow connections from local host — necessary
host 127.0.0.1
# same as 255.255.255.255 127.0.0.1
#
# allow connections from any host
# on the 131.234.223.0 network
255.255.255.0 131.234.223.0

So we set up our securenets to look like this:

host 127.0.0.1
255.255.255.0 10.10.10.0

And tried to connect to the server:
rob@rob-kubuntu3:~$ ip addr show dev wlan0 |grep "inet "
inet 10.10.10.210/24 brd 10.10.10.255 scope global wlan0
rob@rob-kubuntu3:~$ ypcat -d nisdom -h rhel5-64-2 passwd.byname
No such map passwd.byname. Reason: No such map in server's domain
rob@rob-kubuntu3:~$ ping -c1 rhel5-64-2
PING rhel5-64-2 (10.10.10.213) 56(84) bytes of data.
64 bytes from rhel5-64-2 (10.10.10.213): icmp_req=1 ttl=64 time=0.823 ms

--- rhel5-64-2 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.823/0.823/0.823/0.000 ms

Removing the /var/yp/securenets file allowed us access, so it wasn’t firewall or rpc or portmap issues, to the best I can determine. Adding “host 10.10.10.210″ also worked and allowed the client access. So what’s wrong with the format / man page?

Now, the important thing here is that the script sets very specific error codes (we have 16 defined) based on different error states, so that a tool like HP Opsware can give us different reports based on the exit status. When run with “0″ for no logging, this works great, but it requires the controlling tool to capture logs, and not all do (especially cheap “for” loops in a shell script.)

But when run with logging enabled, all of the fancy error code handling (45 lines of subroutines’ worth) gets lost, because “$!” is equal to the status code of the “tee” command. Bash scripters out there will say “but what about $PIPESTATUS ?” If we could use bash, the code would be:
#!/bin/sh
DO_LOG=$1
LOGNAME="`hostname`.out"
if [ "$DO_LOG" -eq "1" ]; then
# Logging is turned on, so relaunch ourself with logging disabled, and tee the output to the logfile
sh $0 0 | tee $LOGNAME
exit ${PIPESTATUS[0]}
fi
#... Do lots of things in the script
exit $ERRORCODE

(Note the single line change in the conditional exit.)

But, I don’t have the luxury of bash (thanks AIX and FreeBSD and Solaris 8), so we needed to get fancy…
#!/bin/sh
DO_LOG=$1
LOGNAME="`hostname`.out"
if [ "$DO_LOG" -eq "1" ]; then
# Logging is turned on, so relaunch ourself with logging disabled, and tee the output to the logfile
cp /dev/null $LOGNAME
tail -f $LOGNAME &
TAILPID=$!
sh $0 0 >> $LOGNAME 2>&1
RETURNCODE=$?
kill TAILPID
exit $RETURNCODE
fi
#... Do lots of things in the script
exit $ERRORCODE

In this last example, we’re creating the empty logfile by copying /dev/null to the logname, then starting a backgrounded “tail” command on the empty file. Because we haven’t disconnected STDOUT in the backgrounding, we will still get the screen output we desire from “tail”. The script now only writes *its* output, with redirected STDOUT and STDERR, to the log file, which is already being tailed to the actual screen. At the end of the script, we capture the true exit code, clean up the tail ugliness, and exit with the desired status code.

This does have a serious downside that if the script encounters and error and exits, the “tail” is left running indefinitely on Linux and Solaris, since the kernel there will simply scavenge the process to be owned by init. So, if you take this method, be very careful to capture all errors you may possibly encounter. Or, just use a better scripting tool.

So, to turn off console (not X terminal, but tty) beeps, you can do one of the following:
1) (This is my preference)

echo blacklist snd_pcsp >> /etc/modprobe.d/blacklist.conf


2) (I’ve done this, but it doesn’t affect all software)

for i in 1 2 3 4 5 6
do
setterm -blength 0 > /dev/tty$i
done

3) (Only works per shell if ~/.inputrc is included)

echo set bell-style visible >> ~/.inputrc


Enjoy more-sane editing from ttyX in the future!

Anyways; Workstation 6.5 has been giving me problems.  Because of the newness of KDE4, I initially thought it was a KDE problem, but it turns out it’s something between Workstation 6.5 and Ubuntu 8.10.  I just ran the “adapt –dist-upgrade-devel” command from the Ubuntu wiki to upgrade, and upon reboot, I couldn’t “ctrl-alt-ins” or “ctrl-alt-del” to log into my Windows VM, my “Windows/Start” key on the keyboard wouldn’t respond, and my arrow keys wouldn’t work.  Incredibly, when I’d hit the “down” arrow, I’d get the Windows Start menu pop up!!

Fix is easy, edit /etc/vmware/config and add the line below like:

sudo vim /etc/vmware/config
:$
A (that's vi-command for "go to the end of the file, and start writing a new line")
xkeymap.nokeycodeMap = true


Have to restart your VMs for this change to take effect. Thanks to Duncan Epping for this fix (he posted it in the forums, where I found it).

With my recent upgrade of that same laptop to Kubuntu Gutsy Gibbon, I kept the laptop-mode.conf file a bit closer to the maintaner�s version. There are some changes to the �dirty-writeback-centiseconds� and the �dirty-background-ratio� values from what I posted, and my issue seems to have gone away. I�ve been able to go back to running my Windows 2003 SBS server with a Centrify DirectControl lab environment and a RHEL 4 Oracle 10g server attached at the same time.

The configuration files that work MUCH better are attached here:

laptop-mode.conf

cpufreqd.conf

For completeness the error I was getting was the same:
/tmp/vmware-config1/vmnet-only/userif.c:630: error: �const struct sk_buff� has no member named �h�
when trying to build the VMNet module – VMMon built and inserted perfectly. Downloaded 6.0.1 and installed it, and I�m back and in the game.

However, because I mostly design Windows networks, I also run VMWare Workstation 6 with the following VMs: Windows XP Pro joined to primary domain (full workstation with Office 2003, Visio, Outlook (and EMC EmailExtender plugins), Windows Admin Pack, Resource Kit, SQL Enterprise Manager, and Exchange Admin Pack), Windows Vista Enterprise, Windows 2003 DC, Exchange, SQL server, Windows XP Pro joined to VM domain, RHEL 4, RHEL 5, and a Live-CD system that I often use to test bootable CDs. And a sysprep�d Windows install.

All that, plus Evolution caching my email and Firefox being disk-happy (did you ever �strace -p $(pgrep firefox) -e trace=open,close,read,write�? It�s busier than Evolution during an offline mail check!), means my 7200 RPM 160GB SATA disk gets hammered. Me also using laptop-mode-tools changing my vm.dirty_writeback_* settings and read/write cache isn�t helping either, I�m sure.

Today and yesterday I ran into an issue where my disk would begin a sync that would last 10-20 minutes, leaving me unable to work the entire time that was happening. Hunting down WHAT was causing this, however, was even more frusterating than it happening (If I shut down any of the 3 above-mentioned programs, the problem went away – it only happened with all 3 open). In Windows, you can open Task Manager, go to the �Process� tab, click �View-> Columns� and add �IO Write Bytes� and �IO Read Bytes� and watch the numbers count up. Or you can use Perfmon and look at IO reads/writes/bytes per second or total, and know immediately what�s causing all your disk IO pain. I still don�t know how to do this in Linux.

First, any hunt for �disk utilization� and �Linux� on Google directs you to hundreds of sites, forums, and blogs evangelizing the wonders of �df� for disk utilization. Yes, it�s really nice to know how much free space I have on my hard drives- that�s why I have SuperKaramba to tell me. But when a problem hits and leaves me unable to work, it�s useless.

�iostat -k 1? is great – you�ll know immediately which disk is being used, and how hard. But on a laptop with a single disk, you already know.

�top� sorted by process-state will show you what�s in �waiting on IO� state, but not what�s CAUSING the IO that�s causing everything else to wait.

�sar� seems to be the only tool that can provide per-process IO stats, but it has to be pre-set up to write to a log. And I can�t begin to guess how well that will work when my disk is at 100% utilization (peaked at 120tps today).

So if anyone knows of any way to know what�s causing disk IO in a �right now� fashion, please comment or email me. And if you�re curious more about my problem:

1. Only happens when VMWare (with a guest), firefox, and Evolution are all running.
2. VMWare with multiple guests runs fine, and never has this issue.
3. rauch@lt00-bofh:~$ free
total used free shared buffers cached
Mem: 3348960 1099216 2249744 0 68668 533124
-/+ buffers/cache: 497424 2851536
Swap: 6000268 0 6000268
4. Happens with Laptop_mode disabled or enabled, on AC or on battery
5. �sync� causes the exact same symptoms, leading me to believe that somehow I�m getting a LOT more dirty pages than my parameters are set at.
6. dirty_background_ratio
1
dirty_expire_centisecs
60003
dirty_ratio
60
dirty_writeback_centisecs
60003
7. For now, I just close Firefox when I have VMWare open, which means I spend a lot more time in IE than I want to.

As a final note, I�ve updated my Linux EVDO post here with my new built-in card�s info.