The Virtualization Practice

Tag Archive for HA

StorageNetworking

There are many different types of metrics pertaining to storage and IO that can be grouped into Performance, Availability, Capacity, Economics and Energy (PACE). Every application or workload has some characteristics attribute of Performance, Availability, Capacity, Economics and Energy that can be further broken down into metrics that are more detailed.

I saw a question get posted on twitter that kind of intrigues me a little. The question was pretty straight forward. “How many virtual machines should I be able to run on a host?” That is really a fair question in itself but what I find intriguing is that this is the first question he asks. Is this really the first thing administrators think to ask when designing their environment? After all there is no set formula on how many virtual machines you can run on a host. You can be a little more exact when working with VDI because for the most part all the virtual machines would be set up pretty much the same way and the numbers can be a little more predictable. That would not be the case when working with server virtualization. You are going to have servers all with different configurations and amount of resources provisioned to the virtual machines. This variation is what will change your slot count and the amount of virtual machines you can run on the host.

With the release of vSphere 4.1 there have been some great enhancements that have been added with this release. In one of my earlier post I took a look at the vSphere 4.1 release of ESXi. This post I am going to take a look at vSphere 4.1 availability options and enhancements. So what has changed with this release? A maximum of 320 virtual machines per cluster has been firmly set. In vSphere 4.0 there were different VM/Host limitations for DRS as well as different rules for VMware HA. VMware has also raised the number of virtual machines that can be run in a single cluster from 1280 in 4.0 to 3000 in the vSphere 4.1 release. How do these improvements affect your upgrade planning?

I just finished writing all the content for my next book entitled VMware ESX and ESXi in the Enterprise: Planning Deployment of Virtualization Servers (2nd Edition) which continues the discussion on Dynamic Resource Load Balancing (DRLB). DRLB is the balancing of virtualized workloads across all hosts within a cluster of virtualization hosts without human intervention. This is the ultimate goal of automation with respect to virtualization and therefore the cloud. In effect, with DRLB the virtualization administrators job has been simplified to configuration and trouble shooting leaving the virtual environment to load balance work loads on its own.