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

This week a colleague called me with a VMware ESX problem. He’s doing a Exchange 2007 implementation and he configured a virtual machine which should function as the Mailbox server. He was complaining that the virtual machine took 13 to 15 minutes just to boot and he suspected a storage issue as they had been struggling with the storage for a few days.

I asked him to check the virtual machine performance tab and asked him if he saw anything strange. Nothing! The server had plenty of memory left and was not using very much CPU.

When I asked him how many resources he assigned to the virtual machine his response alerted me. He configured the virtual machine with 16GB of memory and 4 vCPUs!

When I asked him why he gave the virtual machine so much resources his response indicated that he hadn’t read the Virtual Infrastructure best practices and applied the ‘MS, I might use those resources just once during my lifecycle‘ sizing. When we checked the%CPU ready performance statistics the values were astronomical.

So I explained the behavior of the CPU scheduler to him and asked him to reduce the number of vCPUs to 1 or 2 and try again. When I called him the next day he told me that the virtual machine now booted within a minute.

So bottom line: Give a virtual machine the resources it needs for normal every day operation and be very modest. Monitor the virtual machine and adjust the resource settings according to your findings. In this case, less definitely is more and it’s very easy, especially in vSphere 4, to (hot) add resources. And if you do need 4vCPUs, it can be more effective to deploy two 2vCPU virtual machines instead of one 4 vCPU virtual machine.

[Updated: 8-11-2009 10:00]

Lately I keep receiving questions from colleagues regarding virtual infrastructure design using VMware products. So I decided to sum up the best practices I use when designing a new virtual infrastructure. Some of the best practices are based on numbers and calculations but others are pretty obvious. Nevertheless you would be surprised how many environments I’ve encounter were the most basic best practices have NOT been met.

So hereby my list of best practices on:

• ESX(i);
• vCenter;
• Licensing;
• Storage;
• Networking;
• Virtual machines.

If you have additions or new insights please reply.

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Everybody has his or her own opinion. And that’s a good thing …. most of the time. And everybody wants to solve problems or create solutions in their own way. Since we all have our own opinion and we all have a different view of the world around us, we all create different solutions for the same problem. And again, this is a good thing, most of the time.

But every now and then you have to solve a problem in too little time and you ask yourself: ‘Isn’t there anybody that already solved this problem?‘ The answer is almost always: Yes, somebody already solved it.

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