Over the last year, we have made a big push to move our development/test environments to a virtualized environment using VMWare Server. While we have not really encountered serious performance issues with our test servers, my team was reporting very poor performance with running the development virtual machines on their laptops. Now, keep in mind that these are pretty powerful laptops with 3 or 4GB of RAM, a T9300 dual-core processor, and a 7200RPM SATA hard drive. So there was more than enough horsepower to run WebSphere Portal in a virtual machine. However, the facts did not bear it out and in fact my team was reporting that running the virtual machine was in fact slowing their laptops down to a crawl with the constant hard disk access – a build that ought to take 5-10 seconds was taking several minutes. Obviously an unacceptable situation and people had reverted to just using a local WebSphere Portal install on their native OS – the issue with the local installs was that these local installs were not configured with LDAP or all the customizations/configurations that our test VMs have. When I found out about the issue and workaround and the fact that my pet initiative had fallen by the wayside, I felt challenged to resolve this issue. I tried it out on my own laptop and was able to reproduce this issue, and 2-3 hours later, I had the issue resolved.

To reiterate, the root cause of our performance woes was the excessive disk I/O being done by VMWare. Even though, we had plenty of RAM on our laptops and had more than enough RAM allocated to the Virtual Machine, what I noticed was that while VMWare would start by using significant amount of host RAM, over time it would release that RAM back to the host O/S. Once I realized what was going on, I did some Google searches and looked up the VMWare settings help, and had a resolution to my issue.

Here are the changes that I made to my laptop and to the VMWare settings to improve performance -

1. Disable Memory Page Trimming

   VMware Server uses a memory trimming technique to return unused virtual machine memory to the host machine for other uses. Although trimming usually has little impact on performance and might be needed in low memory situations, the I/O caused by memory trimming can sometimes interfere with disk-oriented workload performance in a guest. To disable memory page trimming, check the Disable memory page trimming check box (Select: VM > Settings > Options > Advanced), and click OK.

   Given that I have enough RAM on my laptop, my first step to improve performance was to disable memory trimming for guest VMs.

2. Disable real-time anti-virus protection

   Given the size of the VMWare virtual disk files and given that they are continuously being written to, I figured that my real-time anti-virus protection (Symantec AV) was probably not helping any with my disk I/O performance. So, I went ahead and excluded the VMEM (Virtual Memory – .vmem extension) and VMDK (VMWare Virtual Disk – .vmdk extension) files from the real-time scan.

3. Disable memory sharing

   When the first two steps did not yield the results I wanted, I did some more searching and stumbled upon this default VMWare feature of page sharing that enables VMWare to save on memory usage if multiple virtual machines are running the same operating system or the same applications. I am not sure how this works in my scenario where I only have 1 virtual machine running at a time, but it certainly appeared to me that VMWare was scaling back its memory usage resulting in unnecessary disk I/O and this seemed like a possible culprit. I disabled memory sharing by adding a setting sched.mem.pshare.enable in my virtual machine configuration (.vmx) file like this:

   sched.mem.pshare.enable = “FALSE”

Well, these 3 settings did the trick for me! No more VMWare performance woes – the guest VM performs adequately without affecting performance of other applications on my host OS! Keep in mind, that you should also look into defragmenting your host disks and also shrinking your virtual disks for the best performance. I had already done these steps before I spent the time to track down the performance issues. Now, my team can go back to adopting the VMWare development virtual machines!

This is a quick blog about some start-up issues that I ran into with VMWare Server during my initial experimentation with it. I also go into the solutions for these issues.

The first real basic issue that I ran into was that I wanted to add a hard disk to an existing virtual machine in VMWare Server, and when I clicked on Edit virtual machine settings, the Add button on the Hardware tab in the Virtual Machine Settings pop-up window was grayed out. This turned out to be a quick fix – essentially, the virtual machine was running and I could not edit the settings in that VM state – once I stopped the VM, I could change the hardware configuration on the VM to my heart’s content.

The next issue I ran into was that I could not simultaneously access the host machine from the VM and the VM from other machines on our network. My resolution for this issue (there might be other solutions as well) was to configure 2 ethernet adapters on the VM – one ethernet adapter was set up to be a NAT type network connection while the second adapter was set up to be a Host-only type network connection. Note that I also tried having a Bridged type network connection instead of a NAT type – that worked just fine in my office environment, but at home with my wireless router the bridged connection did not work out.

Another issue that I ran into was with accessing the hard disk on my host computer – this was not really a VMWare issue but a Vista issue. Essentially, I could not access the default admin share c$ as by default these admin shares are blocked for network access in Vista. You can find the workaround for this issue here.

These were relatively stupid and basic issues that I ran into – may not have run into them if I had read the docs but docs are for wimps!

I have been hearing the virtualization buzz for a couple of years now, but have never really tried it. About a month back, I decided to give virtualization a whirl and downloaded the free version of VMWare – VMWare Server. VMware Server installs on a variety of operating systems including most flavors of Windows and Linux, partitions a physical server into multiple virtual machines, and allows you to run Windows/Linux on these virtual machines. I currently have it installed on my Vista laptop and I love it – VMWare, not Vista just to be clear! I have been creating VMWare images left, right and center. I created development images of WebSphere Portal v6.0, WebSphere Portal Express v6.0, and Lotus Quickr 8.0 on Windows XP. I have another image running XAMPP for Windows – a great package for getting jump started with Apache HTTPD 2.2.4 + Openssl 0.9.8e, MySQL 5.0.45, PHP 5.2.3, PHP 4.4.7, phpMyAdmin 2.10.3, and Zend Optimizer 3.3.0 on Windows. I installed XAMPP to get going with phplist – a vibrant open-source tool for newsletter management. And just today, I was playing with installing Debian Linux on another virtual machine. All in all, I have gone vm-crazy!

Not only have we been creating individual developer virtual machines, but are also setting up our new test servers using VMWare. I am really sold on virtualization in the test/development environment for many reasons including -

1. Simplifies running multiple test environments on a single system even if those test environments use the same resources – for example, same ports.
2. Simplifies backup of test environments.
3. Simplifies creation of copies of test environments – for example, if you have a virtual machine running WebSphere Portal, you can easily copy it off to another developer laptop giving that user his/her own copy of WebSphere Portal.
4. Enables us to easily provision new test servers as needed – this is true for base virtual machines running a specifc OS or complete Web/App Servers.
5. Simplifies the installation of multiple operating systems on a single system for test/development purposes

As we use it more and more, I might get comfortable enough to consider running it in a production environment – or maybe a customer will force it on us! Virtualization is a powerful tool in the tool-chest of an enterprise software developer and if you have not examined it yet, you are wasting time!