Why aren't you thinking about NFS?

I tend to put technologies in three buckets - small, medium, large. It's usually because one is bigger/faster/more expensive than the other and its a quick simple way to put things in context.
If I carve up Storage Area Networks (SANs) in those buckets.

Large - Fibre Channel (i.e. EMC Clariion)
Medium - iSCSI (i.e. Equallogic's PS100/PS300)
Small - NFS (i.e. NetApp)

Last week announcement by Autotrader, got me thinking why is NFS in the small bucket - it's 1 GB just like iSCSI so I decided to redo my mental ranking

Large - Fibre Channel
Medium - iSCSI/NFS
Small - DAS (traditional direct attached storage)

10 GB iSCSI and NFS's I/O vs. 8 GB Fibre Channel - that's could flip it again.

Large - iSCSI/NFS (1/10 GB)
Medium - Fibre Channel (1/2/4/8 GB)
Small - DAS (traditional direct attached storage)

I like this blog's view as well.

"in a few years, the world will realize that using iSCSI or FC SAN with vm-zen-ness is stoopid. "

No one wants to be stoopid.

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

How many more VMs can you fit into a Cluster, Resource Pool or Host?

Given the speed at which most admins are adding new VMs to their environment ("vm sprawl"), every admin has to figure out where to deploy the new VMs. Simply guessing about resource availability will lead to performance problems and downtime. What I am proposing here is a simple 4 step process you can use to determine how many more VMs you can fit into a Cluster, Resource Pool or a host. Here it goes

1. Select a cluster, resource pool or a host
2. Get info on available memory, storage, cpu, disk i/o and net i/o
3. Calculate an average VM footprint in the cluster, RP or host in terms memory, cpu, storage, disk i/o
4. Apply average VM footprint to every resource type to see which resource you will run out of first.That’s how many more VMs you can fit into host, cluster or resource pool

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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

9 capacity bottlenecks in ESX that kill performance

I have compiled a list of "things" that can cause you to run out of capacity resources in your ESX data center and run into performance problems or even downtime:

1. Adding new VMs though uncontrolled VM sprawl
2. Removing hosts from clusters
3. HA enabling your cluster without accounting for fail over
4. Changing Fail Over Capacity setting in a Cluster
5. Increasing reservations in VMs
6. Changing Resource Pool Configurations
7. Power up many VMs that were powered off or in maintenance
8. Natural growth rates in Storage, CPU, Memory and Network utilization
9. Changes in workloads can result in Disk I/O bottlenecks

Did I miss any? Let me know abakman@vkernel.com

Are you ready to SHARE your resources?

Sharing what? Resources? Memory? CPU? Storage?

There is an entire generation of Sys Admins now that has grown up with a distributed computing data center where one application is normally run on one server. This mostly happened because of Windows instability. Most administrators did not want to deal with trying to troubleshoot OS problems and multiple application problems at the same time. The threat of the infamous "Blue Screen of Death" defacto created this one application one server architecture. In this world admins did not have to think about or worry about sharing of resources.

Welcome to server virtualization where sharing of resources IS the primary idea. Sys Admins now will have to get used to the fact that their VM may suffer performance degradation as a result of its neighbor VM running on the same hardware and consuming a disproportionate amount of CPU and memory. So now Capacity Analysis and Capacity Monitoring becomes important again just as it was back in the mainframe days. Sys Admins now have to really pay attention to "Who is consuming what resources". Capacity Analysis is not a one time event. It is an ongoing activity. In fact many System Administrators I have spoken with are already spending a good chuck of their time troubleshooting capacity related bottlenecks in their environment.

The problem will only get worse. As organizations continue to add Virtual Machines at an exponential rate, this problem in fact will get exponentially more challenging. The unpredictability of work load management will make Capacity Analysis a required activity that will have to be performed at least daily. Just because you have used VMWARE Capacity Planner for your initial P-to-V conversion, you have to realize that it was nothing more than initial sizing. As you continue to add more virtual systems to the mix, many of the previous assumptions made by the Capacity Planner will no longer be accurate.

I love virtualization! Let me know what you think and email to abakman@vkernel.com

Alex Bakman