While researching ESX architecture and performance, I came accross a VMWare KB article about the performance impact of shared interrupt lines.

It comes down to this: if you have two controllers on the same interrupt line, and one controller is managed by the console OS while the other is managed by the VMKernel, performance can be impacted. This could be a USB controller that is managed by the console OS and a storage controller that is managed by the VMKernel. Performance is impacted because of context switches between the console OS and the VMKernel.

So, the golden rule is: disable unused controllers such as USB controllers.

By the way: when you configure a controller (such as a storage controller) to be dedicated to virtual machines but shared with the console OS, it is the VMKernel that manages the device.

If you want to change the IP subnets of the host only, NAT or any other network, you can use vmnetcfg.exe.

vmnetcfg.exe can be found in the installation folder, usually C:\Program Files\VMware\VMware Player. VMWare Player needs to be restarted to use the new settings.

It's easy to create a vmdk and vmx file for use with VMWare Player. The VMWare Player is free but does not let you create virtual machines.

Steps:

1. Create VMDK with qemu-img.exe
2. Create VMX with VMXBuilder

1. Create the VMDK

Create a VMDK file with qemu-img.exe. This exe is part of QEMU, downloadable from http://free.oszoo.org/ftp/qemu/win32/release/QemuInstall-0.7.2.exe.

Command line:

• qemu-img create -f vmdk Windows2003Server.vmdk 10G

This creates a vmdk that can grow up to 10G. It will actually create a file of about 1,2MB.

2. Create the VMX

Create a .vmx file. To easily do that, use http://sanbarrow.com/vmxbuilder.html. You will find a batch file there that will create a vmx for you.

The batch file just asks questions. You can:

• set the virtual hardware type
• set the OS
• define SCSI and IDE disks: of course, refer here to the disk you made with qemu-img.exe
• define an ISO file to attach
• define network cards
• set advanced properties like virtual SMP, clustering support, etc....
• ....

Once you have the VMX, open it with VMWare player and you are done. You can now start installing an OS to the empty disk. It is easiest to just use an ISO file of the OS installation cd and configure the iso in VMXBuilder. When you start the VM, you will boot from the ISO!

I decided to play around with Xen a bit, just to see how Xen works as opposed to VMWare's virtualization products. Now you have to understand that I am not a Linux expert. In fact, my knowledge of Linux is limited, to say the least. Luckily, there are quite a lot of docs out there that describe what you have to do (as always).   more »

This tool optimizes the size of virtual machine disks. It works with Virtual PC/Server and VMWare Workstation/GSX. The tool is run inside the VM. Windows guests only!

After running, you can compact the file with the tools provided by Microsoft and VMWare.

The difference before and after can be enormous. Check out the website and review with the links below. I will certainly give it a try!

http://www.invirtus.com

Review with screenshots

On VMTN, a whitepaper can be found that describes how to configure VMWare ACE as the user's primary desktop environment. Basically, VMWare ACE is automatically started in fullscreen mode when the user logs on to the machine. The user does not interact with the host machine.

It is an interesting concept that has some advantages. The main advantage is that the underlying hardware of the guest is always the same. That makes deploying the os, patches and applications simpler. Because of the many ACE policies you can set, you can prevent copying the virtual machine to another location. ACE also includes a packet filter so that network access can be restricted on the host and the guest. In addition, the virtual machine can be set to expire at a certain date.

According to information in this document, it should be ok to run another copy of Windows XP (or 2000) in a virtual machine while Windows XP is used as the host as long as you have some kind of volume licensing agreement. Better doublecheck with Microsoft before you think about deploying a VMWare ACE solution though.

VMWare ACE as a primary desktop environment

NetIQ has announced the availability of AppManager modules to manage VMWare Virtual Infrastructure (GSX, ESX).

It is not a very cheap solution though (5000$ per server).

Microsoft has released Virtual Server R2 to manufacturing and also announced pricing. The prices are extremely low:

- Standard edition (up to 4 CPUs): $99
- Enterprise edition (up to 32CPUs): $199

The only difference between the versions is the amount of physical CPUs that are supported. There is no SMP support within a guest OS on Virtual Server R2.

With features like this and an incredibly low price, it will be hard to convince customers to use VMWare's GSX Server. I still prefer GSX because of the performance, ease of use by providing both a web interface and a GUI, and the flexible networking features.

VMWare has also cut the price of GSX Server. The price is not as low as the R2 price, but definitely a big difference compared to the previous price points.

Some of the new features in the R2 release:

- Host clustering: see earlier post
- iSCSI support: allows you to create a "guest" cluster accross two R2 boxes
- x64 support: host only (you cannot run 64-bit guests)
- many others such as improved PXE support etc...

Intel is ready to release VT-enabled desktop processors. They already released Xeon CPUs with VT. VT (Virtualization Technology) will make it easier to deal with hard-to-virtualize x86 instructions. Virtualization vendors deal with these hard-to-virtualize instructions in different ways. It is important to note that VT technology helps with CPU virtualization, not with memory or I/O devices virtualization.

Virtualization software will need to be written to take advantage of VT. ESX 3.0 will use it, as will Xen.

Important to note here is that VT support in Xen will allow you to run an unmodified operating system in Xen. Before VT (and AMD's Pacifica), a modified guest OS was required. This technique (paravirtualization) meant low overhead (2%-8%) but prevented you from running Windows as a guest.

Microsoft has released a document with details about Virtual Server 2005 R2 host clustering. This is similar to the solution by VM6 for VMWare GSX in that a virtual machine (guest) is configured as a clustered resource. A regular MSCS cluster can be configured to fail over guests to another node in the case of failure.

Full details here: Virtual Server Host Clustering Step-by-Step Guide for Virtual Server 2005 R2

Check it out here.

Here's a floppy image with FreeSCO that you can use in VMWare as a software router. Although its main purpose is routing, it also has firewall functions. It works with the standard vlance nics and not with vmxnet nics.

It's great to simulate different subnets, for example, when you are doing an AD site design etc...

Download

VM6 is a company that has a piece of software that integrates VMWare GSX with MSCS (Microsoft Cluster Server). In essence, a virtual machine is made a clustered resource.

The software monitors a clustered VM and when it fails, the virtual machine is started on the other MSCS node.

A 30-day evaluation version can be downloaded from their site.

Check out this whitepaper from Veritas (Symantec). It explains how Veritas Cluster Server for Linux works with ESX to provide high-availability.

When VMWare releases version 3.0, this product is probably less useful because ESX 3.0 supports clustering with DAS (Distributed Availability Service).

esxRanger is a product from VizionCore that allows you to create backups of a virtual machine's vmdk file while it is running. You run the product from a Windows machine which makes it very easy. Check some of the screenshots below:

The product can be used entirely from the GUI or command line.

We did some tests with the product and it works as advertised. We only had one issue: the rights to the restored vmx file were not properly set. The root user did not have execute rights on the file, which prevented us from opening a remote console.

There are built-in scripts and other free scripts on the net that can do the same thing but using those requires a bit more knowledge. The advantage of VizionCore (over free tools from the net) is of course that there is a support structure behind it which makes it more suitable for enterprise use.

Technorati : esx, vmware

VMWare ESX has the vmkusage tool to collect and display performance data. When vmkusage is configured with vmkusagectl install, it will schedule cron jobs to get the performance data and to generate graphs. You can see the performance data using http://esxserver/vmkusage.

The freeware tool vmktree uses the same performance data but displays it better (screenshot). While the graphs in vmkusage are generated every 5 minutes, the graphs in vmktree are generated real-time. An interesting feature is realtime stats. It shows the result of esxtop in a browser window every x minutes.

Technorati : vmware virtualization