Virtual Host Development: Part 2

Last week I made the case for using virtual hosts for software development purposes. So this week we’re going to actually try it out. There are a number of considerations to make before we get stuck in so let’s go …

Choosing a Virtual Host Manager

As far as I can tell there are two main equivalent software products for virtual host solutions. They are: Microsoft Virtual PC 2007 (MVPC) and VMware Workstation 6 (WS6). The most notable difference between the hosts is that WS6 costs (at time of writing) $189 and MVPC is free.

However, free comes at a cost. There are a number of disadvantages (for me at least) with MVPC that mean that I will be ponying up the cashwa for vmware’s offering.

  • Guest Display Hardware – Since we have a virtual host it also has a virtual display card. The one that sits inside MVPC is only capable of screen resolutions upto 1600×1200. Since I have a wide-screen display that is set to 1920×1200 it’s a bit of a waste. However vmware can also display on multiple monitors making use of dual head displays.
  • Guest Support – Yes I love Linux and I have to say (because I tried it) that trying to create an Ubuntu virtual guest on Virtual PC was like trying to herd cats. I’d get one part working only to find that something else was bust, whilst it’s possible it’s a pain. If you decide to go ahead with this you should take a look at this article which explains the hoops you must get your kitty’s through. In theory, I guess, you should be able to get any x86 OS that works in WS6 working in MVPC (as long as it isn’t 64 bit). So far though, and this is an observation based on one data point, I think the virtual hardware in WS6 must be more generic than MVPC.
  • Guest OS Tools – Both MVPC and WS6 require you to install additional tools after the core OS install that enhance the operation of the virtual machine. Why I couldn’t really figure out exactly what the tools do it seems reasonable to assume that they’re useful. Indeed it’s not until you install the tools on WS6 that you can access the higher resolutions. With WS6 then it provides tools for Linux where as MVPC does not. Whether this makes an observable improvement to the WS6 experience for Linux would require more time to tell ..
  • Host OS Support – VMware will run on Linux. So should I decide that I want to take my removable disks and put them somewhere else I could. At least in theory
  • Converters – WS6 has a free ‘converter’ which allows the creation of WS6 virtual windows (only) hosts from MVPC ones. Which is nice. Not only that though the converters are bootable so that you can create a virtual ‘copy’ of an already installed non-virtual OS. Whilst I did successfully convert MVPC hosts I didn’t try and virtualise an existing host
  • Snapshot Manager – vmware has a snapshot manager which makes the management of snapshots a lot simpler to comprehend. You get a sort of snapshot time-line that you can chose from and cycle through. MVPC has a similar concept but it’s not as clean.

Snapshot Manager

The virtual host manager you chose will depend on what you need. For me MVPC is not a choice, however there are probably a fair few people who could get good results from MVPC making the benefits of WS6 not that important. Since you can download a trial version of WS6 I would suggest you at least try it before deciding. To me WS6 product feels mature and the user interface seems more intuitive. Your mileage may vary.

For the remainder of this discussion I will talk about using WS6. Whilst you could in theory use MVPC and mostly apply the same ideas the two are not equivalent, as already discussed.

Creating The Host

Having settled on vmware I should say a little about the settings I chose. I’m not saying that these are ideal but for development purposes they seemed like sensible defaults to me. Firstly I instructed WS6 to create me a custom virtual host. For the most part I used the presented defaults but deviated on a few items:

  1. Non-Local Disk – When I say non-local I mean non-local to the host OS. If the disk of a virtual host is the same physical disk of the non-virtual host then you will have I/O performance issues. This is especially true for laptops that tend to have slower hard disks than their desktop equivalents (4200rpm vs 7200rpm). That’s why I went and bought an external drive enclosure and speedy hard disk before I started
  2. Memory – Since these hosts are development hosts I’m probably going to need some RAM, especially since I intend to run VS2005 on the windows host. Therefore I chose 1Gb RAM for the windows hosts and 512Mb for the Ubuntu host. Note that for windows changing the amount of memory after the OS is activated can force you to reactivate your license. So getting it right-enough first time would be a bonus. After running both systems on this configuration for a couple of weeks I can say that the settings are convenient enough for me and I’ve not noticed any excessive paging and performance is fine.
  3. Networking – I elected to chose NAT as my virtual networking setup. This puts my virtual hosts on their own subnet, they access the internet as the non-virtual host and then the results are routed back by vmware. The other alternative might be to bridge virtual and real host but this, I think, would make my virtual host a peer of the real one on the domain. Something I want to avoid for now.
  4. Disk Size – I allocated 80Gb disks to each host. In practice I would probably only use about 10% of that space but WS6 does not allocate the space all at once. This means I only use as much space as I need. This obviously incurs an overhead because the disk is allocated on demand. However I wanted to see if this really causes a noticeable problem before I elect to allocate all the disk at once. Keeping the space to a minimum obviously has advantages for backup purposes but also (I would guess) mean that snapshots take less time.

Building The Host

Obviously I must now load an appropriate OS onto each of my virtual hosts. You do this by simply attaching an ISO to the machine and installing in the normal way. Once installed you should install the VMware tools that improve the integration between your host and guest OS. After installing the extensions (and not before) you should activate your license on Windows based-hosts.

Next you should apply all the updates that are necessary to make your host a good netizen, either through Microsoft Update or whatever package manager your OS uses.

It was at this point that I ran into an issue with Ubuntu which relates to the networking. By default Ubuntu 7.10 turns ‘roaming’ network mode on and this doesn’t play nice with WS6. So turning it off and selecting DHCP insted was needed.

Network Roaming Mode Is Bad

Once built and patched I created checkpoints for both systems to rollback to or clone. This will be useful when I need to create a ‘test’ host for deployment or system testing.

Stack ‘Em High

One of my complaints about developing for Windows is the height of the development stack. Not only do I have to install dev studio but I have to install a bunch of service packs, add-ins and 3rd party software, and their service packs, to have anything like a workable development system. The problem is, when something goes wrong and your installation gets knackered in some way (it’s happened to me twice in the last year) you can kiss goodbye to 1 days development time whilst you sort it out.

That’s why, once I had all the development tools installed, I then took another snapshot to record the base development install so I can revert to it in seconds rather than hours. It’s my intention that when I went to install a new software tool I will clone a snapshot, install the software and see what it does before I commit to installing it into the main disk image.

Shared Disks

One important feature of having a virtual host is being able to easily share data between the guest and host OS. The clipboard works fine for a lot of things but when you want to expose a 1Gb ISO from the host to the guest it becomes a bit painful. Sure you could FTP the files from one to the other but that would be a pain. What you really need is to expose a part of the host file system to your virtual machine. Under windows and WS6 this results in the creation of \\.host URI that is accessible from the guest windows OS.

However for Ubuntu it failed because the installation of the tools failed without me noticing!! It turns out there is a bug in one of the vmware headers that incorrectly sets which kernel API to use. This is one of the problems with Linux I guess in as much as vendors have to release source code drivers because of all the different versions the guest OS could be. However, because it’s source code it’s also easy to fix! By following the instructions on the Ubuntu forums I had the matter resolved in minutes.

Accessing Domain Hosts

There’s a couple of problems with interacting with other network hosts when using virtual hosts.

  1. If you’re developing on a shared network and you are unable to make your virtual machine a peer on the network then you will probably have chosen NAT networking. This, as discussed, puts you machines on their own subnet. The consequence of this is that you will need to start using qualified domain names to be able to access the hosts that are in the same domain as your non-virtual machine. This isn’t a huge discomfort and it’s arguably the right thing to do if you’re embedding those names into software that you’re writing anyway.
  2. The second problem relates to the use of Windows authentication. Applications that use windows authentication (like SQL Server Management Studio) will fail because your virtual machine is not part of the domain. One solution is again to make your virtual host a peer on the network. Whilst this would be the ideal it might create implications for how you’re going to manage a battery of virtual machines and might result in some loss of liberty because you’re system administrator got scared. The solution is to use a feature of windows networking that allows the user to manage multiple identities. This will allow you to enter a set of credentials for each machine that you will connect to. After making these changes applications that use Windows authentication work flawlessly.

Stored Passwords


After spending a week of development on virtual machines I like it. I don’t notice any performance lags on the widows host everything works beautifully. On Linux I occasionally have mouse problems where the mouse refuses to roll over a particular screen area. This needs to be reset by disconnecting control from the VM (Ctrl+Alt) and then clicking (to regain the control) and trying again. It’s possible that this problem is something to do with known mouse problems, perhaps more investigation is required.

The WS6 ribbon makes switching between machines and displays simple. The ribbon also makes using WS6 analgous to using remote desktop which feels natural.

WS6 Ribbon

It had been my original intention to run only my development needs inside the virtual machines and keep the real machine for my office needs like e-mail, spreadsheet and word processing. However that becomes awkward to juggle between and means that I sometimes miss e-mail or IMs when the development host is maximized over the top of the host desktop. Having said that though maybe not getting distracted is a good thing 😉

However, I’m starting to think that I should adjust the windows virtual machine RAM and install all of the office applications and IM software into the windows development host. Reducing the host OS to simply a shell for the VMware software. All in all though, I’d recommend all developers to try it out at least. It ticks all the boxes I wanted and after the setup and configuration it makes development a saner process. Which has to be good, right?