Managing Jumpbox virtual machines with Redhat Enterprise

I have long run the great Jumpbox virtual machines with Redhat EL 5 and Xen, but they have always had a different start up process to other machines, as the configuration file is slightly different.

I decided it would be much neater to control all the Xen based virtual machines with virt-manager, the GUI VM management tool supplied with RH5.4

It was a lot easier to do than I thought, basically I created a fully virtualized machine, with a phoney disk image. It is important to remember that the jumpbox VM's are not paravirtualized, and use qemu for their device's.

Now all I had to do was open the file that virt-manager had created in the /etc/xen sub-directory and edit it.

I changed the MAC address of the virtual NIC to that it was intended to be, and changed the virtual disk images that it pointed too.

The full file is below , and shows all the important parts. Voila , it run's like a charm and is now just another Xen virtual image that I can manage with the standard tools.

name = "fs-wiki"
uuid = "2d10f9db-a6df-ce50-c2b0-8255d80af734"
maxmem = 512
memory = 512
vcpus = 1
builder = "hvm"
kernel = "/usr/lib/xen/boot/hvmloader"
boot = "c"
pae = 1
acpi = 1
apic = 1
localtime = 0
on_poweroff = "destroy"
on_reboot = "restart"
on_crash = "restart"
device_model = "/usr/lib64/xen/bin/qemu-dm"
sdl = 0
vnc = 1
vncunused = 1
keymap = "en-gb"
disk = [ "file:/var/lib/xen/images/moinmoin-1.1.9/disks/root/root.hdd,hda,w", "file:/var/lib/xen/images/moinmoin-1.1.9/disks/data/data.xen,hdb,w", ",hdc:cdrom,r" ]
vif = [ "mac=00:16:3e:16:d2:24,bridge=xenbr0,script=vif-bridge,vifname=vif12.0" ]
parallel = "none"
serial = "pty"

If you want real virtual speed with your Jumpbox appliances use Xen not ESXi

As you will have seen on my blog recently we had a situation that meant I had to move one of our Jumpbox virtual appliances from a failed Xen server to a new ESXi server. Now these servers are exactly the same specification, HP DL380 G5 with 32GB RAM and 2 x Dual Core Intel Xeon CPU's , so not exactly supercomputers, but more than enougth to do what we want with them.

Well here is the thing, Jumpbox say that VMware are one of their main supported platforms and , Tier 1 partners I think they call it, and open source Xen is Tier 3. So how come then the virtual appliance runs significantly faster on Redhat Enterprise than it does on Vmware ESXi? When I say significantly, I'm not joking. The virtual appliance is the moinmoin wiki. On the ESXi platform trying to edit a post is painfully slow, 30 seconds to open the editor. On Xen it is 1-2 seconds at most, so I don't need a stop watch to see something is wrong.

I have gone through the settings for the Vmware server, something I don't have to do with Xen, and given it garanteed resources and CPU power, no difference. I could, if I fancied wasting a small part of my life, investigate the Advanced settings for the ESXi server, but again why would I when with Xen it just flys?

I don't know the answer thats for sure, and especially when you know that the Jumpbox appliance is running with the QEMU hardware emulator on Xen, as it's not para-virtualized! Emulators as I'm sure you know are not supposed to be that fast.

I think I'm going to chat to Jumpbox about this, as it really does seem odd. The only thing that may have affected the performacne is the fact that I had to migrate the appliance to ESX format from Server format, but surely once this process is completed the virtual image should be good to go.

Upgrading VMware tools in your Jumpbox virtual appliance

If you migrate a Jumpbox virtual appliance between virtual hosts, for instance, form a VMware Server or VMware workstation to an ESXi server, the already installed configs and installed drivers maybe out of date or the wrong version, and the management screens will complain and let you know about it. This is very easily cured.

Firstly , make sure you have ssh enabled on your virtual machine, and log in as root or admin. Once logged in, go back to your management application, which for ESXi will be the vSphere Client, and select the virtual machine and select install vmware tools from the right button click on that virtual appliance.

This will have effectively mount an iso with the files on, which you must now mount from your ssh terminal window using a command like this:

mount /dev/cdrom /media/cdrom - (you may need to create that directory)

They move into that directory and cp the file VMwareTools-4......(whatever).tar.gz to say /tmp

Go into /tmp and untar the above file, and then move into the directory it creates.

Run the following command and hit enter when asked, after reading the output, but for a standard Jumpbox, just hitting enter will do:

./vmware-install.pl

At the end of the process you can either reboot the virtual machine, or type in the following command:

/etc/init.d/networking stop; rmmod pcnet32; rmmod vmxnet; modprobe vmxnet; /etc/init.d/networking start

Make sure you have the semi colons and type it all on one line.

Voila, you now have the latest vmware tools, which means you are running the optimum networking drivers which is important for performance

Using a Jumpbox virtual machine as a mobile aide memoir

If like me you have trouble keeping track of all the technical information that comes across your desk on a weekly basis, then I might just have the answer for you.

I have started to use a virtual moinmoin wiki image from Jumpbox, the virtual machine supplier, which just happens to be free, to record all the detailed technical things I need to remember.

The beauty of this solution, is that as long as I have a Xen virtual server around, I can run up this virtual machine where ever I want and have full access to all my information. It also works with VMware, so you could just as easily use VMware server or player, in my case all this would all be done using Linux as the host.

The thing I like most about it is that it can remain accessible, long after all of the underlying technology has been replaced. You can also backup the data you have put in the wiki with ease, and that can be restored to another virtual machine running on a different form of virtualization, neat huh. Another nice feature of this is that it would be trivial to put this into the cloud for global access or even team sharing, it just gets better ;-). However, not all companies allow unfettered access to the cloud, so it's always a good idea to have access to both.

If you are prepared to pay Jumpbox a few pounds a year, which I would recommend, you can do exactly the same with Mediawiki, which offers more facilities.

Getting a Jumpbox VM to work with Redhat EL 5 64 bit

If you use virtualization a lot , then I'm sure you will have come across a great company that offers a whole range of pre-built open source virtual images. That company is Jumpbox. I have used several of their images with great success, and the time to deploy is extremely quick, especially with VMware ESX or VMware server.

On this occasion though I wanted to get a moinmoin wiki going on a 64bit Redhat Xen server, and the default install script supplied with the images is for 32bit systems. It fails, telling you it can't find qemu, which is true as it won't given the default script. Also note that you must have hardware virtualization switched on in the BIOS to get these images to work on 32 or 64 bit systems.

You have to make a minor change to one part of the config file, JumpBox.xen , simply because this is where RH put the 64bit version of qemu.

Here is the section that needs changing.

devfiles = [
'/usr/lib/xen/bin/qemu-dm',
'/usr/lib/xen-ioemu-3.0/bin/qemu-dm'
]

I changed the line '/usr/lib/xen/bin/qemu-dm' to '/usr/lib64/xen/bin/qemu-dm'

You then use the start script "xm create -c JumpBox.xen", and the virtual machine is then visible in the virtual manager on the host server.