VMGuru.nl – I choose (a virtual) life!

A couple of weeks ago I had a problem where the connection between a snapshot and its parent disk was gone. The parent was a raw device mapping pointing to a LUN on a SAN. This all happened during a migration from one type of SAN to another. For the migration we had to remove the Raw Device Mappings from a virtual machine in order to move it with Storage VMotion. After the move the original RDM had to be re-added to the virtual machine. The final step was to copy the original data from the RDM to a new disk.

One of the steps in our migration plan was to make sure that there weren’t any snapshots on the virtual machine. This procedure was used during the whole migration. One of my colleagues and I were planned for the last batch of servers.

Everything went OK during the migration of this server. All steps were executed without errors. The server started like it always starts. Even the first check by the administrators looked good.

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During the last month I have been very busy building a new infrastructure at a client site. I’m responsible for the overall technical solution and the basis, a VMware vSphere infrastructure build on five Dell PowerEdge R805’s, Dell EqualLogic PS5000 and 6000 storage and Cisco switches for LAN, DMZ and IP storage networking.

Just before the customer initiated their functional test period we discovered that the overall Windows network  performance was slow. We did several test like copying an 8 GB file from local vmdk to local vmdk and VM to VM and found that the storage performance was no issue but the network performance was very slow.

In the last few years that I have been working with virtualization I have always been a fan of a static network configuration. Meaning, when I configure ESX networking I like my network interfaces and physical switch ports to be configured at 1000MB full duplex if the switch/network interface combination allows it. The idea is that if you purchase gigabit network interfaces and switches you know the maximum speeds. So you configure it to run at it’s maximum capacity, eliminating overhead and using as much bandwidth as possible purely for data transfer.

So when we experienced slow network performance I had a colleague check the Cisco LAN switches for errors, drops, packet loss or any other flaw which might indicate a speed or duplex mismatch. None were found so I assumed that the network configuration was not the issue. But as we know by now, ‘Assumption is the mother of all fuck-ups!‘.

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For about three weeks ago I was asked by my colleague Erik Scholten to help him out with his VMware View project for our Service Center. I thought this is my change to explore the ins and –outs of VMware View. The infrastructure for VMware View was already build by Erik on four Dell servers and a Dell Equallogic SAN. After one week of figuring out the architecture and everything up and on it, Erik told me he had to leave for another project right away. A lot of trust in my hands with a dead line in sight over a couple days.

Let me sum things up that Erik couldn’t finish;

• Windows Vista client customization failed.
• Windows XP client poor performance.

I started with the Windows Vista customization problem, but first let met tell you something about the client.  Vista was deployed with Windows BDD 2007 in a virtual machine and customized using the build-in Sysprep by my colleagues of the IT team for the customer. After my colleagues had installed all the software it was time to convert the VM into a template waiting to be deployed. But unfortunately it is not that easy as just reading the administrator guide and do what it says. This is how I tackled these problems:

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With the addition of VMware View your environment gains complexity. Before adding components like VMware View or Lab Manager you only have one point of logging in your virtual enviroment, vCenter Server. Now you have to look into the textfiles itself if you want to do some real troubleshooting.

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When I am troubleshooting I like to have a list of items I can check for either in my head or on paper. Amongst the knowledge base articles of VMware, I found an article about troubleshooting VMs that are having network connection issues.

The article is provides items you can check for when a VM is having connection issues. And with each item they are giving a link to other helpful articles.

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