Want awesome performance in VMWARE ESX?

Of course! we all do! So let's talk about how to get there. To achieve stellar VMware ESX performance you have to remove ALL bottlenecks in your environment. Remember your performance will only be as fast as the slowest "link" in your performance equation.

Here is the list to start removing performance bottlenecks:

1. Make sure that all of your hosts have sufficient RAM and do not over commit on memory utilization. If your workloads force the host to start swapping memory to disk, kiss your performance goodbye. There is a huge difference in speed between accessing memory internally and doing physical i/o to disk!

2. Make sure your CPU is not over utilized. Checks the processor ready queue to see how long threads are waiting to run. Extended period of time indicates a problem. Also check the overall processor utilization over a week or a month. Keep the overall utilization under 80%

3. As you scale up your ESX environment you will run into disk i/o bottlenecks. Make sure that you places your most mission critical VMs on the fastest storage available to you

4. Understand the timing of your workloads to identify when or if constraints develop in memory utilization, cpu, and disk i/o. Spread out the workloads by changing when they run i.e timing or move workloads to different hosts to mix it up.

How to predict future capacity bottlenecks

Your virtual data center is growing. You are adding a ton of new VMs every week. Wouldn't it be really cool if you head a "crystal ball" that told you in how many days you will run into capacity bottlenecks and what type of bottlenecks it will be (cpu, memory, storage) ?

Now you can. Join Vkernel's beta program for Capacity Bottleneck Analyzer that will kick off in early March

Servers are no longer a "Resource Boundary"

One of the hardest concepts for System Administrators new to virtualization to understand is the shared resource management. VMware ESX makes it possible to share resources namely memory, cpu, storage and network not only inside a physical host, but also across multiple physical hosts. The resources are pulled together to create one massive resource pool captured in a concept called a cluster. Even resources inside clusters can be further subdivided into many Resource Pools. For admins who are only used to dealing with physical servers as resource boundaries this can be confusing, especially when it comes to planning and management of capacity. For example when monitoring or determining resource capacity, Admins must now take into consideration how all resource boundaries are affected. Looking just at physical servers is no longer an option!

How many new VMs are you adding per week?

How many new VMs are you adding per week? This is very important question, because it has major implication to capacity availability in your ESX data center and ultimately performance. Every VM you deploy will consume cpu, memory, storage and network resources. It will also add additional disk I/O. It is easy to see how, if uncontrolled, you can quickly run out of resources and develop capacity bottlenecks. Of course the trick is to figure out which resource you are going to run out of first? Will you hit the bottleneck in memory, cpu, storage, disk i/o or network? The answer is it really depends on your environment, but in most cases the first bottleneck is memory. Why? Remember you were able to virtualize servers, because they were under utilizing CPU. That is what enabled you to combine 8+ plus servers on one piece of hardware. When you think about memory, it is a different story. Just because your servers are now virtual, it does not mean they are consuming less memory. Hence that's why in most environments the first capacity bottleneck is memory. What do you think the second capacity bottleneck you are likely to hit? Let me know at abakman@vkernel.com