VMWare ESXi 4.0 and Boot from SAN

VMWare have just released the free VMWare ESXi 4.0.

I have just tested and it now supports Boot from SAN. WOOT!! I have been looking into using USB drives as a way to boot my VMWare farm servers, but am a little nervous about the lack redundancy. So now I can carve out 2gb of redundant storage from my SAN for each server and save on having local disks that are very much under utilised.

It also looks like you can install the Free version direct to USB Drive rather than having to hack together something from the ISO and using DD or winimage to flash the USB.

This is an excellent move from VMWare and I look forward to reporting back on any other new features i find.

And as an a-side the Cacti Graphs found on this site still work under the new version. Now to find out if there is SNMP support in this release or not (I dont suppose I will be given everything I want in one go!)

Shortcut to hosts file on Windows

This one was shown to me a while back but I needed to use it today and remembered how much easier it is.

To quickly access the hosts file go Start -> Run -> Type drivers -> Ok.

This will bring up the folder before the hosts file, just double click into the etc directory from there.

The other method is to create a new shortcut on your Start Menu or Desktop with the following as the target

%windir%system32notepad.exe "c:WINDOWSsystem32driversetchosts"

Two easy methods to access your hosts file.

RS232 (Serial) Control of LG LCD TV via MythTV

I got sick of having a remote control for everything, so I have started down the path of using RS232 (Serial) control where I can. Currently that is only my TV, but when the Decoder and DVD player get replaced I will be looking for models with remote control capability (I know I could use an IR blaster, but that can impede using the real remote and looks kind of ugly).

So I started by deciding the basic features I used on my TV all the time and how to remap them to the remote control I use for MythTV (I haven’t done every button, I figured if I need to use the remote once a month then so be it). The features required for me were:

  • On/Off
  • Aspect Ratio
  • Input (DTV, Comp, RCA, VGA)

I found the codes required to send to the TV on the LG website somewhere. If your TV supports RS232 there should be a document somewhere that describes the protocol used you will just need to find it.

I found the following code somewhere, it was originally used just to send and receive data via a serial port so I have modified it to send what I need to the TV and removed everything else.

Just drop the following in a file called tvcontrol in /usr/local/bin

#!/usr/bin/python

#allows you to capture the command switches
import sys

#get serial features for python
import serial

#this next line sets up the serial port to allow for communication
#and opens the serial port you may need to change
#ttyS0 to S1, S2, ect. The rest shouldn't need to change.
ser = serial.Serial('/dev/ttyS0', 9600, 8, serial.PARITY_NONE,
         serial.STOPBITS_ONE, xonxoff=0, rtscts=0, timeout=1)

#default COMMAND is bogus
COMMAND = "nope"
aspect169 = "kc 00 02n"
aspect43 = "kc 00 01n"
poweron = "ka 00 01n"
poweroff = "ka 00 00n"
inputdtv = "kb 00 00n"
inputav1 = "kb 00 02n"
inputcomp1 = "kb 00 04n"
inputpc = "kb 00 06n"

if sys.argv[1:] == ['--aspect169'] :
    COMMAND = aspect169

if sys.argv[1:] == ['--aspect43'] :
    COMMAND = aspect43

if sys.argv[1:] == ['--poweron'] :
    COMMAND = poweron

if sys.argv[1:] == ['--poweroff'] :
    COMMAND = poweroff

if sys.argv[1:] == ['--inputdtv'] :
    COMMAND = inputdtv

if sys.argv[1:] == ['--inputav1'] :
    COMMAND = inputav1

if sys.argv[1:] == ['--inputcomp1'] :
    COMMAND = inputcomp1

if sys.argv[1:] == ['--inputpc'] :
    COMMAND = inputpc

#This is when it actually writes the command to the serial port.
ser.write(COMMAND)

#all done now close the port.
ser.close()

The following is an example of using this script with LIRC, this is a small part of my lircrc file. This map the buttons that I use on my DVICO remote control.

begin
    remote = *
    button = live
    prog   = irexec
    config = tvcontrol --aspect169
end
begin
    remote = *
    button = folder
    prog   = irexec
    config = tvcontrol --aspect43
end
begin
    remote = *
    button = tv_onoff
    prog   = irexec
    config = tvcontrol --poweron
end
begin
    remote = *
    button = power_onoff
    prog   = irexec
    config = tvcontrol --poweroff
end
begin
    remote = *
    button = dtv
    prog   = irexec
    config = tvcontrol --inputdtv
end
begin
    remote = *
    button = mp3
    prog   = irexec
    config = tvcontrol --inputav1
end
begin
    remote = *
    button = dvd
    prog   = irexec
    config = tvcontrol --inputcomp
end
begin
    remote = *
    button = cpf
    prog   = irexec
    config = tvcontrol --inputpc
end

You mileage my vary, you will need to understand how your remote control functions and what the current button assignments are.

Another possiblity is to have the tvcontrol script run via a Cron entry or controlled via a webpage, use your mobile phone as a remote instead. The possiblities are endless. Have Fun.

Simple .NET XML Tutorial

I needed to build an application the other day that used XML to talk to a web service, but I wanted to deal with raw XML rather then using anything based on WSDL and RPC. This was the first time I had written anything that used XML before so I started googling for code examples and tutorials.

There wasn’t much clear documentation out there on exactly what I wanted to do so I ended up using a couple of code examples I found in the end (links provided below for original source) and modifying them for my needs.

The end result is extremely simple to understand (however the information was not easy to find) so I thought I would post the details here in hopes that someone else wanting to do the same thing ends up finding this article rather than searching for hours and not finding exactly what is required. (As an a-side, most of what I found online was regarding using premade XML files, and the generation of XML files and not generating and sending the XML request on the fly). Also I wasted a bit of time because of my lack of knowledge on how various Streams work together, but that is another issue entirely.

The following is code for C# but should apply to other .NET based languages (with an appropriate change of syntax).

Required Namespace Imports

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.IO;
using System.Net;
using System.Threading;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml;

Code

WebRequest req = WebRequest.Create("http://URLHERE/WebService");
req.Method = "POST";
req.ContentType = "text/xml";
Stream requestStream = req.GetRequestStream();

XmlTextWriter xml = new XmlTextWriter(requestStream, null);

xml.WriteStartDocument();

// The DocType will be different for most situations, this
// is what works for me.
xml.WriteDocType("Request", null, "somefile.dtd", null);
xml.WriteStartElement("Request");
xml.WriteStartElement("InfoRequest");

// These values could come from any source
xml.WriteElementString("Username", "<>");
xml.WriteElementString("Password", "<
>");
xml.WriteElementString("Info", "something");
xml.WriteEndElement();
xml.WriteEndElement();

// When Close() is called the request is sent to the server
xml.Close();

// Use a WebResponse Component to retrieve the response
WebResponse rsp = req.GetResponse();
XmlTextReader xmlin = new XmlTextReader(rsp.GetResponseStream());

while (xmlin.Read())
{
  if (xmlin.NodeType == XmlNodeType.Element)
  {
    if (xmlin.Name == "Info")
    {
      String info = xmlin.ReadString();

      // Do something with returned data

    }
  }
}

xmlin.Close();
rsp.Close();

There are plenty of useful tutorials out there based on XmlTextReader and XmlTextWriter that can explain how to use them to read and write XML. So I wont cover that here. My biggest problem was finding out how to generate the XML and send it straight to the server without having to save to a file.

References: