System Center Virtual Machine Manager for Beginners (Part 2)

If you would like to read the other parts in this article series please go to:

Introduction

In the first part of this article series, I spent quite a bit of time explaining why System Center Virtual Machine Manager is important, and why you need it if you are running Hyper-V in your organization. In this article, I want to continue the discussion by showing you how to get started with Virtual Machine Manager.

The Virtual Machine Manager Components

As is the case with most Microsoft server products, System Center Virtual Machine Manager is designed to be modular. There are a number of different components that you need to be aware of prior to installation.

The first of these components is the VMM Management Server. The management server is the component that does all of the heavy lifting. It is the core Virtual Machine Management Server component that is responsible for processing commands and for running the underlying VMM service. The management server is also responsible for coordinating communications between all of the various components.

The next component that you need to be aware of is the VMM database. The VMM database is an SQL Server database that stores all of the configuration information that is used by System Center Virtual Machine Manager. This database also stores things like profiles and service templates (more on those later in this article series).

The third component that you need to be familiar with is the VMM console. The VMM console is the graphical user interface for System Center Virtual Machine Manager. When working with System Center Virtual Machine Manager, you will typically spend most of your time working within this console.

As you probably know, Microsoft has been working hard over the last few years to base all of their server products on PowerShell. As such, it should come as no surprise that Virtual Machine Manager includes a PowerShell interface known as the VMM Command Shell.

The last major component that I want to discuss is the VMM library server. As the name implies, the library server’s job is to host the VMM library. The library is one of the most important features within Virtual Machine Manager. The library acts as a collection of resources that can be used for virtual machine deployments. These resources can include things like virtual hard disks and templates. Library resources tend to be file based, so the library server’s job is to share the folders that contain the library resources.

Virtual Machine Manager Scalability

In the previous article, I explained that one of Virtual Machine Manager’s jobs was to improve scalability by providing an organization level view of virtual machine resources, rather than limiting the administrator to working with virtual machine hosts on a server by server basis (as is the case with the Hyper-V Manager). Because providing scalability is such an important part of Virtual Machine Manager’s job, I want to spend a moment discussing the degree of scalability that Virtual Machine Manager provides.

Microsoft provides some numbers that indicate what you can expect in terms of Virtual Machine Manager scalability. It is important to note however, that the numbers cited by Microsoft are theoretical maximums. There is also a practicality aspect to consider. If you were to deploy Virtual Machine Manager onto a server that barely meets the minimum hardware requirements then it is unrealistic to expect to be able to efficiently manage large scale environments.

It is also worth noting that Microsoft’s scalability numbers have changed over time. System Center 2012 SP1 introduced dramatic improvements to Virtual Machine Manager scalability. This service pack provides the same scalability numbers as System Center 2012 R2 Virtual Machine Manager. The figures that I will be referring to in the remainder of this section are based around this service pack and on System Center 2012 R2 Virtual Machine Manager.

With that said, Virtual Machine Manager can support up to 1000 virtual machine hosts. In case you are wondering, the previous limit was 400. You will notice that I used the phrase “virtual machine hosts” as opposed to “Hyper-V hosts”. The reason for this is that although Virtual Machine Manager is primarily designed to be used with Hyper-V, it can also be used to manage Citrix XenServer and VMware ESX hosts. As such, System Center Virtual Machine Manager can be used to manage dissimilar hypervisors through a single management interface. There are some limits that come into play when managing non-Microsoft hypervisors, but this isn’t really the time or place to get into that discussion.

Just as Virtual Machine Manager limits the total number of virtual machine hosts that you can manage, there is also a cap on the total number of virtual machines that can be managed. The limit is 25,000 virtual machines.

There are also some limits that come into play from a management perspective. Virtual Machine Manager supports up to 50 concurrent management clients. In other words, up to fifty copies of the management console can be open, or up to 50 VMM Management Shell sessions can be established. If a mixture of the two tools are being used then the total number of connections cannot exceed 50.

It is also worth noting the VMM Management Server is not typically installed directly onto a Hyper-V host. As such, the VMM Management Server behaves similarly to a proxy. The administrator issues management commands through the management console or through the management shell and those commands are sent to the VMM Management Server. The VMM Management Server receives the commands and interprets them. It then transmits the necessary commands to the target virtual machine host.

The actual management tasks are not performed locally on the management server, but are instead performed on a remote virtual machine host. That being the case, most management tasks are treated as jobs (as opposed to local commands that run instantaneously). The reason why I mention this is because there is a limit to the total number of concurrent jobs that can be run. That limit is 250. Incidentally, Virtual Machine Manager’s Job History Records can keep track of the last five million jobs that you ran.

One last thing that I want to mention is that Virtual Machine Manager is designed to provide multi tenancy for virtual server environments. Virtual Machine Manager has a theoretical limit of 1000 tenants. In reality however, the actual number of tenants that can be supported may be much lower. The reason for this is that Virtual Machine Manager also places a limit on the number of user roles that can be created. That limit is also 1000. As such, the only way that Virtual Machine Manager can support 1000 tenants is if each tenant consumes only a single user role. User roles and multi tenancy will be discussed in detail later in this series.

Conclusion

Now that I have discussed the basic components and scalability limitations of Virtual Machine Manager, it is time to move forward with a deployment. I will walk you through the deployment in Part 3 of this article series.

If you would like to read the other parts in this article series please go to:

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